U.S. patent number 6,602,994 [Application Number 09/248,246] was granted by the patent office on 2003-08-05 for derivatized microfibrillar polysaccharide.
This patent grant is currently assigned to Hercules Incorporated. Invention is credited to Mary Jean Cash, Anita N. Chan, Herbert Thompson Conner, Patrick Joseph Cowan, Robert Alan Gelman, Kate Marritt Lusvardi, Samuel Anthony Thompson, Frank Peine Tise.
United States Patent |
6,602,994 |
Cash , et al. |
August 5, 2003 |
Derivatized microfibrillar polysaccharide
Abstract
A method for producing derivatized microfibrillar
polysaccharide, including but not limited to cellulose, derivatized
by steric and/or electrostatic forces, where the electrostatic
forces are provided by anionic charge or by a combination of both
anionic and cationic charge, by stabilizing and/or
microfibrillating a polysaccharide starting material. A method of
modifying the rheological properties of a composition of matter
using derivatized microfibrillar polysaccharide. Method of
improving coatings, paper manufacture, and the stability of
emulsions, dispersions, and foams using a derivatized
microfibrillar polysaccharide. Compositions that include
derivatized microfibrillar polysaccharide, including paper
compositions, comestible compositions, non-comestible spreadable
compositions, and emulsions, dispersion, and foams.
Inventors: |
Cash; Mary Jean (Wilmington,
DE), Chan; Anita N. (Wilmington, DE), Conner; Herbert
Thompson (Landenberg, PA), Cowan; Patrick Joseph
(Hockessin, DE), Gelman; Robert Alan (Newark, DE),
Lusvardi; Kate Marritt (Chadds Ford, PA), Thompson; Samuel
Anthony (Wilmington, DE), Tise; Frank Peine (Wilmington,
DE) |
Assignee: |
Hercules Incorporated
(Wilmington, DE)
|
Family
ID: |
22938284 |
Appl.
No.: |
09/248,246 |
Filed: |
February 10, 1999 |
Current U.S.
Class: |
536/30; 536/100;
536/44; 536/84; 536/91; 536/95; 536/97; 536/99; 536/96; 536/92;
536/90; 536/43 |
Current CPC
Class: |
A61K
8/027 (20130101); A61Q 11/00 (20130101); A61Q
17/04 (20130101); A61Q 19/00 (20130101); C08B
1/00 (20130101); C08B 11/12 (20130101); C08B
11/20 (20130101); C08B 15/00 (20130101); C08B
37/00 (20130101); D21H 17/26 (20130101); A61K
8/731 (20130101); D21H 21/20 (20130101); A61Q
19/08 (20130101); D21H 21/10 (20130101); D21H
21/16 (20130101); D21H 21/18 (20130101) |
Current International
Class: |
A61Q
19/08 (20060101); A61Q 19/00 (20060101); C08B
11/00 (20060101); A61K 8/73 (20060101); C08B
11/20 (20060101); A61K 8/72 (20060101); C08B
1/00 (20060101); D21H 17/00 (20060101); D21H
17/26 (20060101); A61Q 17/04 (20060101); C08B
37/00 (20060101); C08B 15/00 (20060101); C08B
11/12 (20060101); D21H 21/16 (20060101); D21H
21/18 (20060101); D21H 21/14 (20060101); D21H
21/10 (20060101); D21H 21/20 (20060101); C08B
011/00 (); C08B 011/193 (); C08B 011/08 (); C08B
011/12 (); B01J 013/00 () |
Field of
Search: |
;536/30,43,44,84,90,91,92,95,96,97,99,100 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 845 495 |
|
Nov 1997 |
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EP |
|
0845495 |
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Jun 1998 |
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EP |
|
0859011 |
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Aug 1998 |
|
EP |
|
59-84938 |
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May 1984 |
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JP |
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98-95803 |
|
Apr 1998 |
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JP |
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10165823 |
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Jun 1998 |
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JP |
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WO98/02486 |
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Jan 1998 |
|
WO |
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WO98/02487 |
|
Jan 1998 |
|
WO |
|
WO98/02499 |
|
Jan 1998 |
|
WO |
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WO9938892 |
|
Aug 1999 |
|
WO |
|
00 47628 |
|
Aug 2000 |
|
WO |
|
Other References
Cash et al., U.S. patent application Ser. No. 09/522,032, filed
Mar. 9, 2000. .
H. Yokota, J. Polmer Sci., Part C, 24, 423-425 (1986). .
C.H. Haigler, Cellulose Chemistry and Its Applications, Nevell, pp
30-83, (1985). .
N. Morss, J. Ogg, "Some Special Characteristics of Cellulose
Ethers", SCI Monograph, 1966, Vol 24, pp 46-56. .
M. Dolz, J. Bugaj., J. Pellicer, M.J. Hernandez, M. Gorecki, J.
Pharm. Sci. 1997, vol. 86, pp 1283-1287. .
M. Dolz, C. Roldan, J.V. Herraez, R. Belda, P. Sobrino, J.
Dispersion Sci. and Tech., vol. 13 pp 95-113, 1992. .
G. Regdon, I. Eros, Acta Pharm. Hung. 1988, vol. 58, pp 173-180
Chemical Abstracts 109:176212. .
G. Regdon, I. Eros, Acta Pharm. Hung. 1988 vol. 58, pp 193-200
Chemical Abstracts 110:28967. .
I. Eros, A. Mednyanszky, G. Regdon, Acta Pharm. Hung. 1986, vol.
56, pp. 273-282 Chemical Abstracts 106:90079. .
G. Regdon, I. Eros, Acta Pharm. Hung. 1985 vol. 55, pp 68-75
Chemical Abstracts 103:59168. .
J.A. Walecka, TAPPI, vol. 39, pp 458-463, 1956. .
M. Nishiyama, J. Hosokawa, K. Yoshihara, T. Kubo, H. Kabeya, T.
Endo, Trans. of Materials Soc., 1994, vol. 18A, pp 459-462. .
B. Riedel et al., "Novel Polyanion-Polycation-Microfibride Blend
Nonwovens Based on Cellulose Derivatives", Chemical Fibers
International, vol. 49, No. 1, Mar., 1999, pp. 55-57..
|
Primary Examiner: Wilson; James O.
Assistant Examiner: White; Everett
Attorney, Agent or Firm: Edwards; David
Claims
We claim:
1. A derivatized microfibrillar polysaccharide, derivatized to
comprise substituents that provide electrostatic and/or steric
functionality, said electrostatic functionality comprising anionic
charge, wherein the derivatized microfibrillar polysaccharide is
characterized by forming a gel in water at at least one point in
the concentration range of from about 0.05 wt. % to about 0.99 wt.
% based on the total weight of the gel.
2. The derivatized microfibrillar polysaccharide of claim 1,
wherein the polysaccharide in said derivatized microfibrillar
polysaccharide comprises at least one of cellulose, hemicellulose,
chitin, chitosan, guar gum, pectin, alginate, agar, xanthan,
starch, amylose, amylopectin, alternan, gellan, mutan, dextran,
pullulan, fructan, locust bean gum, carrageenan, glycogen,
glycosaminoglycans, murein, bacterial capsular polysaccharides, and
derivatives thereof.
3. The derivatized microfibrillar polysaccharide of claim 2,
wherein said polysaccharide is at least one of cellulose, chitin,
chitosan, pectin, agar, starch, carrageenan, and derivatives
thereof.
4. The derivatized microfibrillar polysaccharide of claim 3,
comprising derivatized microfibrillar cellulose.
5. The derivatized microfibrillar polysaccharide of claim 4,
wherein said cellulose is obtained from at least one of chemical
pulps, mechanical pulps, thermal mechanical pulps, chemical-thermal
mechanical pulps, recycled fibers, newsprint, cotton, soybean
hulls, pea hulls, corn hulls, flax, hemp, jute, ramie, kenaf,
manila hemp, sisal hemp, bagasse, corn, wheat, bamboo, velonia,
bacteria, algae, fungi, microcrystalline cellulose, vegetables, and
fruits.
6. The derivatized microfibrillar polysaccharide of claim 5,
wherein said cellulose is obtained from at least one of optionally
bleached wood pulps produced from sulfite, kraft, or prehydrolyzed
kraft pulping processes; cotton linters; fruits; and
vegetables.
7. The derivatized microfibrillar cellulose of claim 4, comprising
at least one of microfibrillated hydroxyethyl cellulose,
microfibrillated ethylhydroxyethyl cellulose, microfibrillated
carboxymethylcellulose, microfibrillated carboxymethylhydroxyethyl
cellulose, microfibrillated hydroxypropylhydroxyethyl cellulose,
microfibrillated methyl cellulose, microfibrillated
methylhydroxypropyl cellulose, microfibrillated methylhydroxyethyl
cellulose, microfibrillated carboxymethylmethyl cellulose,
microfibrillated hydrophobically modified carboxymethylcellulose,
microfibrillated hydrophobically modified hydroxyethyl cellulose,
microfibrillated hydrophobically modified hydroxypropyl cellulose,
microfibrillated hydrophobically modified ethylhydroxyethyl
cellulose, microfibrillated hydrophobically modified
carboxymethylhydroxyethyl cellulose, microfibrillated
hydrophobically modified hydroxypropylhydroxyethyl cellulose,
microfibrillated hydrophobically modified methyl cellulose,
microfibrillated hydrophobically modified methylhydroxypropyl
cellulose, microfibrillated hydrophobically modified
methylhydroxyethyl cellulose, microfibrillated hydrophobically
modified carboxymethylmethyl cellulose, microfibrillated
nitrocellulose, microfibrillated cellulose acetate,
microfibrillated cellulose sulfate, microfibrillated cellulose
vinyl sulfate, microfibrillated cellulose phosphate, and
microfibrillated cellulose phosphonate.
8. The derivatized microfibrillar cellulose of claim 4, wherein
said derivatized microfibrillar cellulose forms a gel in water
throughout the concentration range of between about 0.01 wt. % and
about 100 wt. % solids based on the total weight of the gel.
9. The derivatized microfibrillar cellulose of claim 4, wherein
said derivatized microfibrillar cellulose forms a gel in water
throughout the concentration range of between about 0.01 wt. % and
about 50 wt. % solids based on the total weight of the gel.
10. The derivatized microfibrillar cellulose of claim 4, wherein
said derivatized microfibrillar cellulose forms a gel in water at
at least one point in the concentration range of from about 0.05
wt. % up to about 0.99 wt. % solids based on the total weight of
the gel.
11. The derivatized microfibrillar cellulose of claim 4, comprising
carboxymethylcellulose.
12. The derivatized microfibrillar polysaccharide of claim 4,
wherein said derivatized microfibrillar cellulose forms a gel in
water at a concentration of less than about 1 wt. % solids based on
the total weight of the gel.
13. The derivatized microfibrillar polysaccharide of claim 1,
further comprising a solvent, wherein said derivatized
microfibrillar polysaccharide is substantially insoluble in said
solvent.
14. The derivatized microfibrillar polysaccharide of claim 13,
wherein said solvent is water, alcohol, or oil.
15. The derivatized microfibrillar polysaccharide of claim 14,
wherein said solvent is water.
16. The derivatized microfibrillar polysaccharide of claim 15,
wherein said derivatized microfibrillar polysaccharide is
derivatized to comprise substituents that provide electrostatic
functionality.
17. The derivatized microfibrillar polysaccharide of claim 15,
wherein said derivatized microfibrillar polysaccharide is
derivatized to comprise substituents that provide steric
functionality.
18. The derivatized microfibrillar polysaccharide of claim 17,
having a molar substitution of less than about 3.0.
19. The derivatized microfibrillar polysaccharide of claim 18,
wherein said molar substitution is less than about 1.5.
20. The derivatized microfibrillar polysaccharide of claim 19,
wherein said molar substitution is less than about 1.0.
21. The derivatized microfibrillar polysaccharide of claim 20,
wherein said molar substitution is less than about 0.5.
22. The derivatized microfibrillar polysaccharide of claim 18,
wherein said molar substitution is between about 0.5 and 3.0.
23. The derivatized microfibrillar polysaccharide of claim 17,
wherein said substituents comprise at least one of hydroxyethyl
groups; hydroxypropyl groups; methyl groups; ethyl groups;
straight- or branched-chain alkyl, alkenyl, or alkynyl groups
having from about 4 to about 30 carbons; aryl, arylalkyl,
arylalkenyl, cyclic, and herterocyclic hydrocarbons having from
about 4 to about 30 carbons; or combinations thereof.
24. The derivatized microfibrillar polysaccharide of claim 23,
further wherein said derivatized microfibrillar polysaccharide is a
derivatized microfibrillar cellulose.
25. The derivatized microfibrillar cellulose of claim 24, wherein
said microfibrillar cellulose is further derivatized to provide
electrostatic functionality with a degree of substitution of less
than about 0.35.
26. The derivatized microfibrillar cellulose of claim 25, wherein
said degree of substitution is less than about 0.20.
27. The derivatized microfibrillar cellulose of claim 26, wherein
said degree of substitution is between about 0.02 and about
0.2.
28. The derivatized microfibrillar cellulose of claim 27, wherein
said degree of substitution is between about 0.10 and about
0.2.
29. The derivatized microfibrillar polysaccharide of claim 1,
wherein said derivatized microfibrillar polysaccharide comprises
electrostatically derivatized microfibrillar cellulose having a
degree of substitution of less than about 0.5.
30. The derivatized microfibrillar polysaccharide of claim 29,
wherein said degree of substitution is less than about 0.35.
31. The derivatized microfibrillar polysaccharide of claim 30,
wherein said degree of substitution is less than about 0.2.
32. The derivatized microfibrillar polysaccharide of claim 31,
wherein said degree of substitution is less than about 0.18.
33. The derivatized microfibrillar polysaccharide of claim 32,
wherein said degree of substitution is less than about 0.1.
34. The derivatized microfibrillar polysaccharide of claim 29,
wherein said degree of substitution is between about 0.02 and about
0.5.
35. The derivatized microfibrilliar polysaccharide of claim 34,
wherein said degree of substitution is between about 0.05 and about
0.2.
36. The derivatized microfibrillar polysaccharide of claim 1,
derivatized to comprise substituents that provide electrostatic
functionality in the form of anionic charge, wherein the degree of
substitution representing substituents that provide electrostatic
functionality in the form of anionic charge is at least about
0.02.
37. The derivatized microfibrillar polysaccharide of claim 1,
wherein said anionic charge is provided by carboxyl, sulfate,
sulfonate, phosphonate, or phosphate groups, or combinations
thereof.
38. Microfibrillar carboxymethylcellulose having a degree of
substitution of between about 0.10 and about 0.20.
39. A paper composition comprising derivatized microfibrillar
cellulose derivatized to comprise groups that provide electrostatic
and/or steric functionality, further wherein said electrostatic
functionality comprises the presence of anionic charge.
40. The paper composition of claim 39, wherein said derivatized
microfibrillar cellulose is microfibrillar carboxymethylcellulose.
Description
FIELD OF THE INVENTION
The present invention relates to derivatized microfibrillar
polysaccharide. More specifically, the present invention relates to
microfibrillar polysaccharide stabilized by steric and/or
electrostatic forces, where the electrostatic forces are provided
by anionic charge, or by a combination of both anionic and cationic
charge.
BACKGROUND OF THE INVENTION
Polysaccharides are often found in nature in forms having fibrous
morphology. Polysaccharides which are not found in nature in
fibrous form can often be transformed into fibrous morphologies
using fiber spinning techniques. Whether the fibrous morphology is
of natural or artificial origin, the polysaccharide will often be
present such that the fibers can be reduced to fibrillar and
microfibrillar sub-morphologies through the application of
energy.
Fibrillar and microfibrillar cellulose obtained in this manner have
been considered for use in applications, including use as additives
to aqueous-based systems in order to affect rheological properties,
such as viscosity. The use level of these materials in aqueous
systems is often on the order of about 2% by weight, below which
these materials have a tendency to poorly occupy volume, and to
exhibit gross inhomogeneities in distribution.
Microfibrillated cellulose and its manufacture are discussed in
U.S. Pat. Nos. 4,500,546; 4,487,634; 4,483,743; 4,481,077;
4,481,076; 4,464,287; 4,452,722; 4,452,721; 4,378,381; 4,374,702;
and 4,341,807, the disclosures of which are hereby incorporated by
reference thereto. These documents, in part, purport to describe
microfibrillated cellulose in stable, homogenous suspensions,
characterized as useful in end use products including foods,
cosmetics, pharmaceuticals, paints, and drilling muds.
Cellulose nanofibrils are characterized in WO 98/02486
(PCT/FR97/01290), WO 98/02487 (PCT/FR97/01291), and WO 98/02499
(PCT/FR97/01297), the disclosures of which are hereby incorporated
by reference. Nanofibrils are characterized as having diameters in
the range of about2 to about 10 nanometers.
EP 845495 discusses cationic cellulose particulate which is
characterized as insoluble, positively charged, and used in water
treatment, specifically to treat water in a paper manufacturing
plant. In paper making this cationic particulate is said to remove
anionic trash from the water. The particles are obtained by
milling, which is stated to reduce particle size uniformly such
that particles are typically round as described by a
length/diameter ratio of approximately 1. Particle size is stated
to be 0.001 mm (i.e., 1 .mu.m), and preferably 0.01 mm (10
.mu.m)
EP 85901 1("EP '011") is directed to a process for obtaining
cationic cellulose microfibrils or their soluble derivatives. The
process is described as including making a cationic cellulose
derivative and processing the derivative through a high pressure
homogenizer to form transparent gels. The product can be dehydrated
and rehydrated. Viscosity measurements are reported on the product
at a concentration of 2% in water. EP '011 indicates that the
degree of substitution ("DS") of the cellulose can range from 0.1
to 0.7, with a DS of between 0.2 and 0.7, 0.3 and 0.6, and 0.5 and
0.6 characterized as representing increasing orders of preference.
The examples show cellulose with a DS ranging from a low of 0.24 up
to 0.72. Gelling is reported to occur above a microfibril
concentration of 10 g/L, or above 1%, in water. EP '011 defines
gelling as occurring when G'>G", where G' is the dynamic storage
modulus and G" is the dynamic loss modulus.
Microfibrillated chitosan is reported to form uniplanar, oriented
sheets upon drying by H. Yokata, J. Polymer Sci., Part C: Polymer
Letters, 24:423-425 (1986). This article mentions that at a level
of 4% chitosan in water, a gel is formed having a viscosity of
26,600 cps (Brookfield, 20.degree. C., rotor #7, 10 rpm). The
microfibrillated chitosan is made by homogenization of commercial
chitosan flakes in a Gaulin homogenizer. The commercial chitosan is
deacetylated using sodium hydroxide.
JP 59 [1984]-84938 discusses a method for producing a chitosan
suspension. Commercial chitosan separated and purified from crabs
and lobsters is pulverized to pieces having maximum length of about
1-2 mm. The pieces are then suspended in water at up to 15%
chitosan, and are run in multiple passes through a high pressure
homogenizer at between 3,000 and 8,000 psi.
It would be desirable to obtain microfibrillar polysaccharides
whose viscosity-affecting properties are achieved without the
presence of cationic functionalities, at least in part because of
the general lack of suitability of cationic materials for use in
foods. It would also be desirable to obtain microfibrillar
polysaccharides that are capable of forming a gel at concentrations
of 1% or less, thereby providing economy and ease of formulation,
while still providing necessary rheological behavior and
homogeneity of distribution.
In addition, there is a continuing need in industry to improve the
stability of commercial emulsions, such as paper sizing emulsions.
At present, one method for stabilizing such emulsions is the
addition of charged materials, such as cationic starches, which may
be added in amounts equal to 10-20% by weight of the size
component. Interaction with anionic components, such as sulfonates,
can also improve stability. However, emulsion failure still takes
place in such emulsions, either through density-driven separation,
also referred to as creaming, or through gellation. It would
accordingly be desirable to develop a material that could be added
to emulsions to provide long-term stability.
SUMMARY OF THE INVENTION
The present intention is directed to derivatized microfibrillar
polysaccharide, methods for its production, and applications for
its use. The derivatized microfibrillar polysaccharides is
derivatized to contain substituents that provide electrostatic
and/or steric functionality; where electrostatic functionality is
present, it includes, but is not necessarily limited to, the
presence of anionic charge.
Polysaccharides suitable for use in the present invention include
cellulose, hemicellulose, chitin, chitosan, guar gum, pectin,
alginate, agar, xanthan, starch, amylose, amylopectin, alternan,
gellan, mutan, dextran, pullulan, fructan, locust bean gum,
carrageenan, glycogen, glycosaminoglycans, murein, bacterial
capsular polysaccharides, and derivatives thereof. Mixtures of
these may be employed. Preferred polysaccharides are cellulose,
chitin, chitosan, pectin, agar, starch, carrageenan, and
derivatives thereof, used singly or in combination, with cellulose
being most preferred. The cellulose may be obtained from any
available source, including, by way of example only, chemical
pulps, mechanical pulps, thermal mechanical pulps, chemical-thermal
mechanical pulps, recycled fibers, newsprint, cotton, soybean
hulls, pea hulls, corn hulls, flax, hemp, jute, ramie, kenaf,
manila hemp, sisal hemp, bagasse, corn, wheat, bamboo,
velonia,,bacteria, algae, fungi, microcrystalline cellulose,
vegetables, and fruits. Preferred sources of cellulose include
purified, optionally bleached wood pulps produced from sulfite,
kraft, or prehydrolyzed kraft pulping processes; purified cotton
linters; fruits; and vegetables.
The derivatized microfibrillar polysaccharides that may be obtained
using cellulose include, but are not limited to, hydroxyethyl
cellulose, ethylhydroxyethyl cellulose, carboxymethylcellulose,
carboxymethylhydroxyethyl cellulose, hydroxypropylhydroxyethyl
cellulose, methyl cellulose, methylhydroxypropyl cellulose,
methylhydroxyethyl cellulose, carboxymethylmethyl cellulose,
hydrophobically modified carboxymethylcellulose, hydrophobically
modified hydroxyethyl cellulose, hydrophobically modified
hydroxypropyl cellulose, hydrophobically modified ethylhydroxyethyl
cellulose, hydrophobically modified carboxymethylhydroxyethyl
cellulose, hydrophobically modified hydroxypropylhydroxyethyl
cellulose, hydrophobically modified methyl cellulose,
hydrophobically modified methylhydroxypropyl cellulose,
hydrophobically modified methylhydroxyethyl cellulose,
hydrophobically modified carboxymethylmethyl cellulose,
nitrocellulose, cellulose acetate, cellulose sulfate, cellulose
vinyl sulfate, cellulose phosphate, and cellulose phosphonate.
The derivatized microfibrillar cellulose of the present invention
may form a gel in water throughout the concentration range of
between about 0.01% and about 100%, or throughout the concentration
range of between about 0.01% and about 50% in water, or at least
one point in the concentration range of from about 0.05% up to
about 0.99% in water. In an alternative embodiment, the derivatized
microfibrillar cellulose of the present invention forms a gel in
water at a concentration of about 0.95%.
The derivatized microfibrillar polysaccharide may be used in the
presence of a solvent, in which it is substantially insoluble.
Examples of solvents include water, alcohol, and oil.
In the case of derivatization with groups that provide
electrostatic functionality, the derivatized microfibrillar
polysaccharides of the present invention may have a degree of
substitution of less than about 0.5, less than about 0.35, less
than about 0.2, less than about 0.18, or less than about 0.1. A
preferred range for the degree of substitution is between about
0.02 and about 0.5, with a range of between about 0.05 and about
0.2 being more preferred. When the derivatized microfibrillar
polysaccharide is derivatized to comprise substituents that provide
electrostatic functionality in the form of anionic charge, the
degree of substitution representing those substituents which
provide electrostatic functionality in the form of anionic charge
is preferably at least about 0.05. Anionic charge may be provided,
for example, by carboxyl, sulfate, sulfonate, phosphonate, or
phosphate groups, or combinations thereof. Where cationic charge is
also present, both charges may be provided by the same groups or
substituent (i.e., the substituent may be amphoteric or
zwitterionic); or, the derivatized microfibrillar polysaccharide
may be derivatized to contain both substituents that contain
anionic charge and substituents that contain cationic charge. In
addition, the derivatized microfibrillar polysaccharides of the
present invention may be obtained by blending two or more separate
derivatized microfibrillar polysaccharides, where at least one has
been derivatized to provide anionic charge, and at least one other
has been derivatized to provide anionic charge, cationic charge, or
both.
When the derivatized microfibrillar polysaccharide of the present
invention is derivatized to contain substituents that provide
steric functionality, the derivatized microfibrillar
polysaccharides may have a molar substitution of less than about
3.0, or of less than about 1.5, or of less than about 1.0, or of
less than about 0.5. The range of molar substitution may be from
about 0.5 to about 3.0. Steric functionality may be provided, by
way of non-limiting example, by hydroxyethyl groups, hydroxypropyl
groups, methyl groups, ethyl groups; straight- or branched-chain
alkyl, alkenyl, or alkynyl groups having from about 4 to about 30
carbons; and/or aryl, arylalkyl, arylalkenyl, cyclic, and
heterocyclic hydrocarbons having from about 4 to about 30
carbons.
In a preferred embodiment the derivatized microfibrillar
polysaccharide contains carboxymethyl cellulose, and has a degree
of substitution of less than about 2.0, preferably less than about
0.35. The range of degree of substitution may be from about 0.02 to
about 0.2, with a range of from about 0.10 to about 0.2 being
preferred.
The derivatized microfibrillar cellulose of the present invention
may form a gel at a concentration of less than about 1% in
water.
In a further embodiment, the present invention is directed to a
comestible composition of matter containing the derivatized
microfibrillar polysaccharide of the present invention. The
comestible composition of matter may, by way of non-limiting
example, be a low fat, reduced fat, or fat-free food spread, such
as a mayonnaise, or a salad dressing. Alternatively, the comestible
composition may contain a pharmaceutically active ingredient. The
derivatized microfibrillar polysaccharide may be used to provide or
improve a controlled, sustained, or delayed release of a component
of the comestible composition, including in particular a
pharmaceutically active ingredient.
In yet another embodiment, the derivatized microfibrillar
polysaccharides of the present invention may be used in
non-comestible, spreadable compositions of matter, such as skin
care lotions or creams, or sunscreen lotions or creams.
The present invention is further directed to a paper composition
containing the derivatized microfibrillar cellulose, and
particularly, though not exclusively, microfibrillar carboxymethyl
cellulose.
The derivatized microfibrillar polysaccharide may be produced by
using a derivatizing step to treat a microfibrillar polysaccharide
to obtain the derivatized microfibrillar polysaccharide.
Alternatively, a derivatized polysaccharide may be microfibrillated
to produce the derivatized microfibrillar polysaccharide. In
another method, the steps of microfibrillation and derivatization
may take place at substantially the same time. In a preferred
embodiment, cellulose is first derivatized with monochloroacetic
acid or a salt thereof under alkaline conditions to produce
carboxymethylcellulose; the carboxymethylcellulose is suspended in
water; and the resulting suspension is homogenized to produce
microfibrillated carboxymethylcellulose.
The derivatizing step may include contacting a non-microfibrillar
polysaccharide with a swelling agent, such as an anionic reagent,
and may take place under alkaline conditions. These alkaline
conditions may include contacting the cellulose with the anionic
reagent in the presence of an alkaline reagent which is sodium
hydroxide, an oxide or hydroxide of an alkali metal or alkaline
earth metal, an alkali silicate, an alkali aluminate, an alkali
carbonate, an amine, ammonium hydroxide, tetramethyl ammonium
hydroxide, or combinations thereof. The derivatization may take
place at high solids.
Microfibrillation may be accomplished by applying energy to a
non-microfibrillar polysaccharide under conditions sufficient to
produce microfibrillar polysaccharide. The non-microfibrillar may
optionally be enzyme-treated before microfibrillizing. More
specifically, microfibrillation may be accomplished using
homogenization, pumping, mixing, heat, steam explosion,
pressurization-depressurization cycle, impact, grinding,
ultrasound, microwave explosion, milling, and combinations of
these. In a preferred embodiment the non-microfibrillar
polysaccharide is passed through a homogenizer under conditions
sufficient to produce microfibrillar cellulose; those conditions
may include a pressure differential of at least about 3,000 psi,
and passing the non-microfibrillar polysaccharide through the
homogenizer at least three times.
The method should be conducted to yield a derivatized
microfibrillar polysaccharide that is substantially insoluble in
the solvent of use. Water is a preferred solvent of use, but other
solvents, including but not limited to alcohols and oils, are
contemplated for various applications.
The present invention extends to derivatized microfibrillar
polysaccharide produced by the above methods.
In an alternative embodiment the present invention is directed to a
method of modifying the rheological properties of a liquid
composition of matter by incorporating the derivatized
microfibrillar polysaccharides of the present invention into the
liquid composition of matter.
This may be accomplished by incorporating the derivatized
microfibrillar polysaccharide into a water-containing system, where
it may be used, for example, to provide scale control and/or
corrosion control. The rheological properties which may be modified
by the derivatized microfibrillar polysaccharide include viscosity,
suspension stability, gel insensitivity to temperature, shear
reversible gelation, yield stress, and liquid retention.
Liquid compositions which may be Theologically modified include, as
non-limiting examples, foods, pharmaceuticals, neutraceuticals,
personal care products, fibers, papers, paints, coatings, and
construction compositions. These include oral care products; creams
or lotions for epidermal application (such as moisturizing, night,
anti-age, or sunscreen creams or lotions); food spreads, including
reduced fat, low fat, or fat free food spreads (such as
mayonnaises); and drilling fluids.
The present invention further extends to a method of improving the
physical and/or mechanical properties of a coating composition by
incorporating, into the coating composition, an effective amount of
the derivatized microfibrillar polysaccharide. The physical and/or
mechanical properties that may be improved in this manner include
film forming, leveling, sag resistance, strength, durability,
dispersion, flooding, floating, and spatter.
The present invention has particular utility in the field of paper
manufacture and treatment. For example, derivatized microfibrillar
cellulose may be used to improve one or more of sizing, strength,
scale control, drainage, dewatering, retention, clarification,
formation, adsorbency, film formation, membrane formation, and
polyelectrolyte complexation during paper manufacture. As a
particular example, the derivatized microfibrillar cellulose may be
used as a drainage aid and/or as a sizing agent. A polyelectrolyte
complex containing the derivatized microfibrillar polysaccharide is
also within the scope of the present invention.
Microfibrillated carboxymethylcellulose is a particularly preferred
embodiment for use in paper applications. During the process of
paper manufacture, the derivatized microfibrillar cellulose may be
used, by way of further example, in a papermaking machine to
increase the rate of drainage and/or dewatering during paper
manufacture; for retention of organic and/or inorganic dispersed
particles in a sheet of paper during its manufacture; to improve
the uniformity of formation of a sheet of paper during its
manufacture; and to improve the strength of a sheet of paper. The
derivatized microfibrillar cellulose may be used in combination
with any of the additives and performance enhancers conventionally
used in paper manufacture, including cationic polyacrylamides;
polydiallyldimethyl-ammonium chloride; cationic starch; derivatives
of cellulose containing ammonium or mono-, di-, or trialkyl
ammonium substituents; derivatives of guar gum containing ammonium
or mono-, di-, or trialkyl ammonium substituents; resins formed by
the reaction of amines and/or polyamines with epichlorohydrin;
aluminum salts; hydrolyzed or partially hydrolyzed aluminum salts;
complexes of hydrolyzed or partially hydrolyzed aluminum salts with
organic or inorganic species; at least one polymer of ethylene
oxide, ethyleneimine, allylamine, or vinylamine; and, at least one
copolymer or terpolymer of ethylene oxide, ethyleneimine,
allylamine, or vinylamine; and combinations thereof. In the context
of retention of organic and/or inorganic dispersed particles, the
particles so retained may include one or more of pulp fines,
fillers, sizing agents, pigments, clays, detrimental organic
particulate materials, and detrimental inorganic particulate
materials.
In another embodiment, the stability of an emulsion, dispersion, or
foam system may be improved by including, in the system, the
derivatized microfibrillar polysaccharide of the present invention.
The derivatized microfibrillar polysaccharide may be added to an
existing system; added to a formulation which will be processed
into such a system; or added during processing of such a
formulation. Where addition takes place before completion of
processing of a formulation into an emulsion, dispersion, or foam
system, the processing conditions used to form the emulsion,
dispersion, or foam may be used to produce the derivatized
microfibrillar polysaccharide as well. Thus, a derivatized
non-microfibrillated polysaccharide (where "non-microfibrillated"
includes an incompletely microfibrillated polysaccharide) may be
added to a formulation prior to completion of processing, and
subsequent processing may then be conducted in a manner that will
microfibrillate the polysaccharide. Alternatively, a
microfibrillated polysaccharide may be added to the formulation,
with subsequent processing conducted so as to derivatize the
microfibrillated polysaccharide. In another variation, both
derivatization and microfibrillation may take place during
processing. Systems which may be treated in this manner include
water-in-oil and oil-in-water emulsions.
The present invention also extends to emulsion, dispersion, and
foam systems produced by the above methods; and, to emulsion,
dispersion, or foam systems that contain the derivatized
microfibrillar polysaccharide of the present invention.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 shows the dynamic mechanical spectra of Example 7, Sample
1.
FIG. 2 shows the dynamic mechanical spectra of Example 7, Sample
2.
FIG. 3 shows the dynamic mechanical spectra of Example 7, Sample
3.
FIG. 4 shows the dynamic mechanical spectra of Example 7, Sample
4.
FIG. 5 shows the dynamic mechanical spectra of Example 7, Sample
5.
FIG. 6 shows the dynamic mechanical spectra of Example 13, Sample
1.
FIG. 7 shows the dynamic mechanical spectra of Example 13, Sample
2.
FIG. 8 shows the dynamic mechanical spectra of Example 13, Sample
3.
FIG. 9 is a transmission electron micrograph of a sample
microfibrillar carboxymethylcellulose prepared as in example 3
below, with a degree of substitution of about 0. 17, negative
stained with urinal acetate, at a magnification of
10,000.times..
DETAILED DESCRIPTION OF THE INVENTION
The present invention comprises derivatized microfibrillar
polysaccharide. Suitable polysaccharides for use in the present
invention include, without limitation, cellulose, hemicellulose,
chitin, chitosan, guar gum, pectin, alginate, agar, xanthan,
starch, amylose, amylopectin, alternan, gellan, mutan, dextran,
pullulan, fructan, locust bean gum, carrageenan, glycogen,
glycosaminoglycans, murein, bacterial capsular polysaccharides, and
derivatives thereof, with cellulose being preferred. The
polysaccharide may be used as is, or spinning may be used to
generate or improve fibrous structure.
Cellulose is a preferred polysaccharide for use in the present
invention. Sources of cellulose for use in this invention include
the following: (a) wood fibers, such as from chemical pulps,
mechanical pulps, thermal mechanical pulps, chemical-thermal
mechanical pulps, recycled fibers, newsprint; (b) seed fibers, such
as from cotton; (c) seed hull fiber, such as from soybean hulls,
pea hulls, corn hulls; (d) bast fibers, such as from flax, hemp,
jute, ramie, kenaf, (e) leaf fibers, such as from manila hemp,
sisal hemp; (f) stalk or straw fibers, such as from bagasse, corn,
wheat; (g) grass fibers, such as from bamboo; (h) cellulose fibers
from algae, such as velonia; (i) bacteria or fungi; and ()
parenchymal cells, such as from vegetables and fruits, and in
particular sugar beets, and citrus fruits such as lemons, limes,
oranges, grapefruits. Microcrystalline forms of these cellulose
materials may also be used. Preferred cellulose sources are (1)
purified, optionally bleached, wood pulps produced from sulfite,
kraft (sulfate), or prehydrolyzed kraft pulping processes, (2)
purified cotton linters, and (3) fruits and vegetables, in
particular sugar beets and citrus fruits. The source of the
cellulose is not limiting, and any source may be used, including
synthetic cellulose or cellulose analogs.
Cellulose is found in nature in several hierarchical levels of
organization and orientation. Cellulose fibers comprise a layered
secondary wall structure within which macrofibrils are arranged.
Macrofibrils comprise multiple microfibrils which further comprise
cellulose molecules arranged in crystalline and amorphous regions.
Cellulose microfibrils range in diameter from about 5 to about 100
nanometers for different species of plant, and are most typically
in the range of from about 25 to about 35 nanometers in diameter.
The microfibrils are present in bundles which run in parallel
within a matrix of amorphous hemicelluloses (specifically
xyloglucans), pectinic polysaccharides, lignins, and hydroxyproline
rich glycoproteins (includes extensin). Microfibrils are spaced
approximately 3-4 nm apart with the space occupied by the matrix
compounds listed above. The specific arrangement and location of
the matrix materials and how they interact with the cellulose
microfibrils is not yet fully known.
For purposes of the present invention polysaccharide microfibrils
refer to small diameter, high length-to-diameter ratio
substructures which are comparable in dimensions to those of
cellulose microfibrils occurring in nature. By way of non-limiting
example, polysaccharide microfibrils may have diameters in the
range of about 20 to about 100 nanometers, combined with lengths
providing high aspect ratios, such as in excess of 100, in excess
of 500, or in excess of 1,000. While the present specification and
claims refer to microfibrils and microfibrillation, the scope of
the present invention also includes nanofibrils (cellulosic or
otherwise), and the rheology modification, stabilization, and other
properties that may be obtained with microfibrils by practicing the
present invention may also be obtained using nanofibrils, either
alone or in combination with microfibrils.
In nature many polysaccharides are not present in microfibril
arrangements, however, by using fiber spinning techniques it is
possible to manufacture fibers from these polysaccharides. In one
embodiment of this invention it is contemplated that fibers spun
from polysaccharides can be derivatized and microfibrillated into
fibrous structures having dimensions on the order of those found
naturally in cellulose. Further background on the structure,
functions, and biogenesis of native cellulose may be found in
Haigler, C.H., Cellular Chemistry and Its Applications, Nevell, pp.
30-83 (1985), the entirety of which is hereby incorporated by
reference.
The derivatized microfibrillar polysaccharide of the present
invention is characterized by being in microfibrillar form, and by
the presence of substituents that provide steric and/or
electrostatic functionality. The amount of substituent present may
be quantified by the degree of substitution, or DS, in the case of
some anionic and cationic substituents, and by the molar
substitution, or MS, in the case of steric substituents. The degree
of substitution, which will vary with the molecular weight of the
polysaccharide, is the average number of substituted hydroxyl
groups per anhydrosaccharide unit, while the molar substitution is
the average number of substituent groups added per
anhydrosaccharide unit. The DS and MS determine the solubility of
the derivatized polysaccharide, and may be readily adjusted to
obtain a derivatized polysaccharide that is substantially insoluble
in the environment of use, whether aqueous or non-aqueous. While
the environment of use will frequently be aqueous, the derivatized
microfibrillar polysaccharides of the present invention have
utility in applications having other solvents or liquid carriers,
such as paints, coating, lacquers, oil-rich foods, inks (including
but not limited to ink-jet inks), personal care products,
cosmetics, and water-in-oil emulsions.
Any suitable method may be used to obtain the derivatized
microfibrillar polysaccharide. In particular, the steps of
microfibrillation and derivatization to impart steric and/or
electrostatic functionality to the polysaccharide may be carried
out separately or combined to arrive at the end result. Therefore,
a non-microfibrillar polysaccharide starting material may either be
derivatized with anionic groups, with both anionic and cationic
groups, or with a blend or mixture of anionic groups and cationic
groups, and then microfibrillated, or may first be microfibrillated
and then derivatized. Alternatively, if the starting material is
microfibrillar polysaccharide, only the derivatizing step would be
necessary, whereas if the starting material is a polysaccharide
that has already been properly derivatized with anionic or both
anionic and cationic groups, only the microfibrillation step is
required.
The degree of substitution (for electrostatic derivatization),
and/or of molar substitution (for steric derivatization), of the
polysaccharide should be sufficiently low so that the derivatized
microfibrillar polysaccharide will be substantially insoluble in
the solvent or carrier that is present in the intended environment
of use. In many applications the solvent or carrier will be water,
an such applications the degree of substitution and/or the molar
substitution should be such that the derivatized microfibrillar
polysaccharide is substantially insoluble in water. However, in
other applications a polar solvent or carrier (such as an alcohol)
may be used having different solubility characteristics, or a
non-polar solvent or carrier (such as an oil) may be used, and in
such cases the degree of substitution and/or the molar substitution
should be adjusted to obtain a derivatized microfibrillar
polysaccharide that is substantially insoluble in the solvent or
carrier used in the application of interest, which, for purposes of
convenience, will hereafter be referred to as the "solvent of use".
Functionally, the derivatized microfibrillar polysaccharide should
be sufficiently insoluble in the environment of use to provide the
desired properties in the intended application.
The presence of substantially insoluble material may be confirmed
by observation of a 1-5% suspension of the material in question in
the solvent or carrier of use under a light microscope at
sufficient magnification to see insoluble material. A size
determination may be made by preparing a suspension of the material
under consideration at approximately 0.1-0.01% in a liquid
non-solvent which is effective in dispersing microfibrils. This
suspension is then dried on a transmission electron microscope
(TEM) grid, the sample is coated to protect it from electron beam
damage, and examined at sufficient magnification and focus to
observe structure in the 1-1000 nanometer range. If microfibrillar
elements are present they can be detected under these conditions,
and the combination of insolubility under the light microscope and
microfibrillar structure under the TEM will indicate the presence
of substantially insoluble microfibrillar material. See FIG. 9 for
an example transmission electron micrograph of a microfibrillar
carboxymethylcellulose prepared as in example 3 below, having a DS
of about 0.17.
For purposes of simplicity, unless specifically indicated otherwise
the term "substituents" shall be used herein to mean chemical
species that provide steric stabilization to the polysaccharide;
chemical species that provide electrostatic functionality to the
polysaccharide through anionic charge; chemical species that
provide electrostatic functionality to the polysaccharide through a
combination of both anionic and cationic charge; and combinations
of the foregoing. In addition, "electrostatic" means either anionic
charge, or a combination of both anionic and cationic charge,
whether as groups both present on a single substituent, or as
groups provided separately on two or more substituents.
"Derivatization" refers not only to chemical reactions resulting in
covalent bonds, but to any process whereby the substituents become
sufficiently associated with the polysaccharide to provide the
rheological and other benefits of the present invention, and may
include, for example, adsorption. Finally, references to the
combination of both anionic and cationic charge on the
polysaccharide include the use of substituents that contain both
types of charge (i.e., amphoteric and/or zwitterionic
substituents); the combined use of substituents which individually
contain only anionic or only cationic charge, resulting in
derivatized polysaccharide with a distribution of substituents that
includes both anionic groups and cationic groups; and, blending of
two or more derivatized polysaccharides where at least one
derivatized polysaccharide includes at least anionic substituents
and at least one other derivatized polysaccharide includes at least
cationic substituents, resulting in a blend that contains both
anionically derivatized polysaccharide and cationically derivatized
polysaccharide. However, "derivatized" does not include the
naturally-occurring, de minimis presence of groups that would only
provide the steric and/or electrostatic functionality required by
the present invention at concentrations higher than those found in
nature. For example, naturally-occurring cellulose may contain very
low levels of anionic charge, which may still be present after
microfibrillation. However, such microfibrillated cellulose is not
"derivatized" as that term is used in the present application, both
because its degree of substitution has not been changed from its
natural state, and because the amount of charge present in such
microfibrillated cellulose would not provide the benefits of the
present invention.
The sequence of steps used to arrive at the derivatized
microfibrillar polysaccharide of the present invention is not
critical. Therefore, the starting material used to make the
derivatized microfibrillar polysaccharide may be in microfibrillar
or non-microfibrillar form. Similarly, the starting material may
already be derivatized with steric and/or electrostatic
substituents, or not. If the starting material is
non-microfibrillar polysaccharide, substituents may be placed on
the polysaccharide followed by microfibrillation, or the
microfibrillation may be carried out first, followed by the
placement of the substituents onto the resulting microfibrils. It
is also acceptable to process polysaccharide into fibrils, place
the substituents on the fibrils, and then further process the
fibrils into microfibrils. Similarly, any non-microfibrillar form
of polysaccharide which already contains such substituents may be
processed into microfibrillar form. Moreover, derivatization and
microfibrillation may be carried out simultaneously.
It will be understood that most, if not all, polysaccharides will
contain some quantity of both microfibrillar and non-microfibrillar
structure both before and after processing, and that the ratio
between the two structures may range from polysaccharide that is
substantially completely microfibrillar, to polysaccharide that is
substantially completely non-microfibrillar. As used herein, the
terms "microfibrillar", "microfibrillated", and the like include
polysaccharides that are substantially completely microfibrillated,
and those which may be substantially microfibrillated while
containing minor but significant amounts of non-microfibrillar
structure, provided the polysaccharide is sufficiently
microfibrillated to confer the benefits afforded by the present
invention.
Processes which minimize the energy needed to produce microfibrils
from non-microfibrillar starting material, and/or which reduce the
amount of water extracted during the process or at its end, are
preferred. In this regard, it should be noted that while the
derivatized microfibrillar polysaccharide of the present invention
can be made by derivatizing a microfibrillated polysaccharide, the
microfibrillation process generally requires less energy, and/or is
more efficient, if the polysaccharide has already been derivatized.
Without being bound by theory, this may be because the presence of
the steric and/or electrostatic functionalities on the
polysaccharide `loosens` the structure of fibril bundles.
The ability to use less energy not only offers cost savings, but
results in less breakage of the polysaccharide microfibrils.
Therefore, microfibrillating a polysaccharide that has already been
derivatized may result in a derivatized microfibrillar
polysaccharide with relatively longer microfibrils as compared to
effecting derivatization after microfibrillation. This is
particularly significant because the energy required for
microfibrillation can be significantly reduced by amounts of
derivatization which are below the level that would render the
resulting derivatized microfibrillar polysaccharide freely soluble
in water. For example, derivatization of cellulose resulting in a
DS on the order of 0.1 or 0.2 will `loosen` the fibril bundles in
cellulose enough to permit microfibrillation using conventional
shearing devices such as a homogenizer, impingement mixer, or
ultrasonicator. These low DS cellulose microfibrils have diameters
on the order of 50 nanometers combined with lengths of up to 500
microns, resulting in aspect ratios in excess of 1,000. While the
low DS allows microfibrillation, it is too low to allow the
resulting material to be fully soluble in the solvent or carrier of
use at the concentrations of interest. Without being bound by
theory, the presence of insoluble regions in the fibers may explain
the data showing maximum gel formation at low DS's. These gels may
be strengthened by weak association of the more hydrophobic
unsubstituted regions.
The stabilization or derivatization is accomplished by the
generation or placement of substituents onto the fibril and/or
microfibril. It appears that the substituents become associated
predominantly with the surface regions of the fibrils or
microfibrils. Regardless of the precise mechanism, in functional
terms microfibril-microfibril contact is inhibited by steric and/or
electrostatic mechanisms or forces. The presence of the
substituents also causes the microfibrils to occupy more volume
than when they are not derivatized, possibly due to inhibition of
contact along at least part of the length of the microfibrils.
Rheological performance of the resulting derivatized microfibrillar
polysaccharide is enhanced at low concentration since volume is
better occupied and the materials are distributed more
homogeneously.
With regard to use of steric force, steric functionality or
stabilization is provided by the formation of a protective barrier
or sheath around a particle (such as a cellulose fibril or
microfibril) to prevent flocculation. For example, it may be
achieved by a material, such as a polymer, being physically
adsorbed on the surface of the particle, thereby preventing two
particles from coming closer than a distance that is twice the sum
of the radius of the particle and the thickness of the adsorbed
layer. As two particles approach and the distance between them
approaches the distance noted above, the adsorbed layers on two
particles interact. This interaction, which as noted may be a
polymer-polymer interaction, results in forces, such as osmotic
and/or entropic forces, that repel the particles. This prevents
flocculation of the two particles, providing stabilization. Because
steric forces are generally provided by the size and/or
configuration of the substituent, a substituent used to provide the
polysaccharide with steric functionality or stabilization may be
neutral, anionic, cationic, amphiphilic, amphoteric, and/or
zwitterionic.
Without being bound by theory, the surfaces of the derivatized
microfibrils appear to have some areas free of the substituents
such that some limited interaction between microfibrils still takes
place. Limited interaction may even be necessary to facilitate
network formation, and may be a cause of the rheological attributes
of interest such as yield stress, shear reversible gelation, and
insensitivity of the modulus to temperature. It also appears that
the length/diameter ratio, or aspect ratio, of the fibrils and
microfibrils also contributes to the performance of the materials
of the present invention.
Any suitable process may be used to generate or place the
substituents on the polysaccharide. For convenience, the possible
processes will generally be referred to collectively as
"derivatization" herein; however, within the context of this
invention, derivatization is used to mean any process which results
in a polysaccharide (including fibrillar and microfibrillar
polysaccharide) having the substituents sufficiently associated
with the polysaccharide to provide the desired benefit(s), and
includes not only chemical reactions resulting in covalent bonding,
but also physical adsorption. In addition, the present application
will refer both to "derivatization" and to "stabilization".
Chemically, both terms refer to the same type of process, namely,
the placement or generation of substituents on the cellulosic
substrate. Functionally, "derivatization" is generally the broader
term, as "stabilization" implies a functionality which is usually
observed primarily or exclusively when the polysaccharide is in
microfibrillar form.
Possible derivatization processes include any synthetic method(s)
which may be used to associate the substituents with the
polysaccharide. More generally, the stabilization or derivatization
step may use any process or combination of processes which promote
or cause the placement or generation of the substituents. For
example, the conditions for treating non-microfibrillar
polysaccharide should generally include both alkalinity and
swelling of the polysaccharide, in order to make the surface of the
fibrils more accessible to the placement or generation of the
substituents. Alkalinity and swelling may be provided by separate
agents, or the same agent may both provide alkalinity and cause
swelling of the polysaccharide. In particular, alkaline agents
often serve multiple purposes, in that they may catalyze the
reaction between the polysaccharide and the substituent, optionally
de-protonate the derivative, and swell open the polysaccharide
structure to allow access of the reagents to carry out the
derivatization.
Specific chemical methods which may be used to achieve the present
invention include but are not limited to generation of anionic
groups (such as carboxyl, sulfate, sulfonate, phosphonate, and/or
phosphate); generation of both anionic and cationic groups (such as
quaternary amine and/or amine); and generation of steric groups, on
or near the surface of the particulate polysaccharide. Alkaline
conditions are preferably obtained by using sodium hydroxide. Any
material that functions as a solvent for the polysaccharide of
choice may be used, and alternative alkaline agents include alkali
metal or alkaline earth metal oxides or hydroxides; alkali
silicates; alkali aluminates; alkali carbonates; amines, including
aliphatic hydrocarbon amines, especially tertiary amines; ammonium
hydroxide; tetramethyl ammonium hydroxide; lithium chloride;
N-methyl morpholine N-oxide; and the like. In addition to catalytic
amounts of alkaline agent, swelling agents may be added to increase
access for derivatization. Interfibrillar and intercrystalline
swelling agents are preferred, particularly swelling agents used at
levels which give interfibrillar swelling, such as sodium hydroxide
at an appropriately low concentration.
These derivatization reactions, if carried out on the original
fibrous polysaccharide structure, may require specific conditions
to maximize the efficiency of location of the derivatization onto
the surface of the polysaccharide. For example, in the case of
cellulose from wood pulp the concentration of the swelling agent
used appears to have an effect on the performance of the final
cellulose. In particular, in using sodium hydroxide it has been
determined that the level of the sodium hydroxide can have a
significant effect on the rheological performance.
It is preferred that derivatization of these fibrous
polysaccharides be performed in a manner which limits the formation
of microfibrils which are soluble in the intended end use
composition, as these may not contribute significantly to the
desired rheological performance. This typically limits the degree
of derivatization which can be made where derivatization at higher
levels would make the polysaccharide soluble in the end use
composition. Specific limits may be readily determined based on the
application in question, but as a matter of general guidance it is
preferred that the degree of substitution (DS) be below about 0.5,
or below about 0.35, or below about 0.2, or below about 0.18, or
below about 0.1.
The derivatization may be carried out in any suitable manner,
including but not limited to suspension in water; in organic
solvent, either alone or in mixtures with water; in solution; and
in high solids, either with water alone or with water and a minor
amount of organic solvent. (For purposes of the present disclosure,
"high solids" refers to a polysaccharide content of greater than
about 25%.
Optional derivatizations or functionalities which may also be
placed on the polysaccharide include but are not limited to short
chain aliphatic and other hydrophobic-type substitutions;
oligomeric and polymeric substitutions; uncharged substitutions, as
for example short chain ethylene and propylene glycols; other
associative-type functionality; surfactant-like functionality;
methyl; ethyl; propyl; and combinations of these. These
substitutions are optional in that they may not be intended for
stabilization of the polysaccharide, and will instead provide
additional functionality such as surface activity, emulsification
power, adsorption characteristics, and the like.
The method for processing a non-microfibrillar form of
polysaccharide into the microfibrillar form may be carried out
either before or after the derivatization reaction. The preferred
method involves the use of a homogenizer on a dilute suspension of
the non-microfibrillar polysaccharide in an aqueous medium. The
aqueous medium optionally may have additives such as swelling
agents, in particular interfibrillar and/or intercrystalline
swelling agents, for example sodium hydroxide, to aid in improving
the ease of microfibril generation. A more preferred method of
microfibrillation involves the use of mechanical energy on an
aqueous suspension of derivatized polysaccharide which has not been
dried. Other microfibrillation processes include, by way of
non-limiting example, use of an impingement mixer; heat; steam
explosion; pressurization-depressurization cycle; freeze-thaw
cycle; impact; grinding (such as a disc grinder); pumping; mixing;
ultrasound; microwave explosion; and milling. Combinations of these
may also be used, such as milling followed by homogenization.
Essentially any method of reducing particle size may be used, but
methods for reducing particle size while preserving a high aspect
ratio in the polysaccharide are preferred. As described previously,
the degree of substitution of the polysaccharide also affects the
ease of processing the polysaccharide to microfibrillar form.
The process to generate the particulate may either be run by the
consumer in the final application such that the particulate is
generated in situ, or be run as described above in aqueous media,
the material dehydrated, and the resulting particulate dried. The
dried particulate of this invention, hereafter referred to as the
ready-to-gel or RTG form, can be rehydrated readily in polar
solvents to obtain the desired theological attributes. Dehydration
can be accomplished by displacing water with less polar solvents
and drying, and can be accelerated by protonation or shielding of
charged groups if they are present.
In terms of general properties, applications where the derivatized
microfibrillar polysaccharide of the present invention have
particular utility include those where the desired rheological
attributes include at least one of yield stress, shear reversible
gelation, and a modulus which is insensitive to temperature. The
ability to provide the rheological attributes described herein also
makes it possible to provide stabilization of mixtures of liquids
and solids having different densities; gel-like properties,
including mouth feel; pumpable gels; stabilization at elevated
temperatures; and, control of hydration and diffusion.
In terms of more specific applications or fields of use, the
utility of the present derivatized microfibrillar polysaccharides
includes, without limitation, foods, personal care products,
household products, pharmaceuticals, neutraceuticals, paper
manufacture and treatment, coating compositions, water treatment,
drilling fluids, agriculture, construction, and spill control
and/or recovery.
In food applications, the derivatized microfibrillar
polysaccharides of the present invention may be useful as rheology
modifiers; as stabilizers, such as by inhibiting creaming or
settling in suspensions; and as non-digestable dietary fiber. They
may also be used to control ice crystal growth during, for example,
ice cream manufacture and storage.
In personal care products, the derivatized microfibrillar
polysaccharides may be used to stabilize emulsions, dispersions,
suspensions, and foams, and may find use in creams, lotions, gels,
and pastes, including those intended for epidermal application.
Representative but not exhaustive examples include sunscreens;
moisturizing or anti-aging creams and lotions; cleaning soaps or
gels; antiperspirants and deodorants, including those in stick,
pump spray, aerosol, and roll-on form; fragrance releasing gels;
lipsticks, lip glosses, and liquid makeup products; oral care
products, including toothpastes, tooth polishing and whitening
agents, and denture care products such as cleaners and adhesives,
and further including use in sorbitol, sorbitol-water mixtures, and
glycerol-water mixtures; products where controlled, sustained, or
delayed release of an ingredient would be desirable; wound care
products, such as ointments (including anesthetic, antiseptic, and
antibiotic ointments), dressings, and products such as ostomy rings
where good liquid retention is desirable; and absorbent products,
such as diapers. The present invention may have particular utility,
not only in personal care products but in other applications, with
products dispersed by a pumping action. The shear-reversible
gelation exhibited by the derivatized microfibrillar polysaccharide
is well suited for pump dispensing, and may be advantageously
combined with its ability to stabilize emulsions, dispersions, and
foams to improve the uniform delivery of product.
In the area of household products, the rheological properties of
the present derivatized microfibrillar polysaccharides, and their
ability to stabilize emulsions, dispersions, and foams, provide
utility in areas such as detergents, shampoos, cleaners, and air
fresheners. Specific examples include, without limitation, laundry
products (including detergents, pre-spotting cleaners, and fabric
treatment compositions, such as softeners); rug and upholstery
shampoos; toilet bowl cleaners (particularly those dispensed in
liquid or gel form); air fresheners; and general purpose cleaning
agents, including liquids, gels, pastes, and foams used in cleaning
and/or disinfecting household surfaces.
In pharmaceutical applications, the derivatized microfibrillar
polysaccharides may have utility in controlled, sustained, or
delayed release formulations; as disintegrants; as dietary fiber;
in wound care, particularly in applications (such as ostomy rings)
where liquid-holding ability is important; and as rheology
modifiers.
In the area of paper manufacture and treatment, the derivatized
microfibrillar polysaccharides of the present invention have
utility in emulsion modification and/or stabilization; sizing;
retention; clarification; absorbence; drainage; formation (such as
by functioning as flocculation aids); deposit or scale control (by
inhibiting the formation and/or growth of inorganic deposits);
water treatment; dewatering; film and membrane formation;
polyelectrolyte cross-linking; removal of detrimental organic
and/or inorganic materials; in paper coatings; and in improving
properties such as stiffness, wet strength, absorbancy, softness,
toughness, tear resistance, and fold resistance.
In the context of paper manufacture, scale control refers to the
prevention of calcium carbonate and calcium oxalate deposits
forming during the pulping process. Scale control can be achieved
by dispersion of salt crystals in the medium to prevent growth and
deposition, inhibition of nucleation, or modification of the
crystal growth mechanism to prevent the formation of crystal forms
that will lead to deposits. The use of derivatized microfibrillar
cellulose having micron and smaller particle size, stabilized with
appropriate functional groups, would serve to control scale deposit
because such microcarriers inhibit the crystal growth which leads
to deposition. Moreover, cellulosic materials would be easier to
recover from the pulping process due to their organic nature.
Preferred functional groups would include phosphate/phosphonate
groups, carboxylate groups, and sulfate/sulfonate groups.
Alternative functional groups and appropriate use levels may be
readily determined by those of ordinary skill in the art, based on
the particular environment of use.
The derivatized microfibrillar cellulose may also be used in a
papermaking machine to increase the rate of drainage and/or
dewatering during paper manufacture; to retain organic and/or
inorganic dispersed particles (such as pulp fines, fillers, sizing
agents, pigments, and/or clays); to retain detrimental organic and
inorganic particulate materials; to improve the uniformity of
formation of a sheet of paper; and to improve the strength of a
sheet of paper. With particular regard to drainage, drainage aids
are additives that increase the rate at which water is removed from
a paper slurry on a paper machine. These additives increase machine
capacity, and hence profitability, by allowing faster sheet
formation. Anionically charged microfibrillar cellulosic
derivatives are capable of greatly increasing drainage, either
alone or in combination with other charged polymers.
The derivatized microfibrillar cellulose of the present invention
may also be used in coated papers, where cellulose derivatives may
be used to control the rheology of the color coating and to provide
water retention, thereby controlling the amount of liquid that
permeates into the base sheet.
In coating compositions, such as paints and inks, the derivatized
microfibrillar polysaccharides can provide rheology modification,
improving properties such as spatter, leveling, sag resistance,
flooding, and floating, and may have particular utility in gel
paints. They may also improve pigment dispersion and/or
stabilization, and function as charge control or flow control
agents, including in inks, such as ink jet inks.
In the area of water treatment, the derivatized microfibrillar
polysaccharides of the present invention can provide scale control,
that is, inhibiting the formation and/or growth of inorganic
deposits in aqueous systems; clarification; flocculation;
sedimentation; coagulation; charge delivery; and softening.
In drilling fluids, the present derivatized microfibrillar
polysaccharides can provide rheology modification, reduce or
prevent fluid loss, and improve secondary oil recovery.
In agricultural applications, the derivatized microfibrillar
polysaccharides of the present invention can be used in soil
treatment, and may provide moisture retention, erosion resistance,
frost resistance, and controlled, sustained, or delayed release of
agricultural materials such as fertilizers, pesticides, fungicides,
and herbicides. They may also be used for crop protection, such as
to minimize or prevent frost damage.
In construction, the derivatized microfibrillar polysaccharides can
be used in dry wall muds, caulks, water-soluble adhesives, and
board manufacture.
In other areas, the derivatized microfibrillar polysaccharides can
be used for control and cleanup of liquid spills, as absorbents for
oil; in general, as stabilizers for emulsions, dispersions, and
foams (including but not limited to oil-in-water and water-in-oil
emulsions); and for emulsification. Stability of commercial
emulsions, such as paper size emulsions, is a recurring issue in
industry. Current commercial emulsions include those which
generally consist of an oil, waxy, or rosin phase dispersed in
water. These dispersions are generally stabilized by the addition
of charged materials such as cationic starches, sodium lignin
sulfonate, and aluminum sulfate. Such materials are generally added
in amounts equal to about 10-20% by weight of the size component.
The resulting dispersions are typically 0.2 to 2 micron particles,
thought to be stabilized by charge repulsion, for example, with the
positively charged starches on particle surfaces repelling each
other.
One cause of emulsion failure is density-driven separation. This
can be limited by increasing viscosity, or internal structure
within the fluid. For example, an emulsion which maintains a
viscosity of less than about 20 centipoise throughout a standard
aging test might have its viscosity increased initially by as much
as 100 centipoise through addition of a viscosifier to the
formulation, and still be within acceptable commercial viscosity,
provided that the viscosity did not then increase over time to
exceed acceptable limits.
One method to accomplish this result would be to use a viscosifying
agent that does not cause a substantial increase in viscosity when
first added to an emulsion formulation, but which does provide an
increase in viscosity during normal processing of the emulsion
formulation to produce the emulsion. This can be accomplished by
including, as an additive to the emulsion formulation,
polysaccharide that has been derivatized as described herein but
not yet microfibrillated. When the emulsion formulation is then
subjected to energy, typically high shear, during the processing
used to turn the emulsion formulation into an emulsion, the shear
will also microfibrillize the derivatized polysaccharide, resulting
in the derivatized microfibrillar polysaccharide of the present
invention, which will be present as part of the emulsion. The gel
produced by the derivatized microfibrillar polysaccharide will then
thin under shear stress but re-form when shear stops. Moreover, the
insolubility of such low DS/MS polysaccharide may cause it to
concentrate at the oil/water interface of oil-and-water emulsions,
rather than the aqueous bulk phase, which may be desirable.
Effectively the same result may be achieved by adding the
derivatized microfibrillar polysaccharide of the present invention
to an emulsion formulation, or to the final emulsion, or at any
point during production of the emulsion. Further variations would
include introducing derivatized polysaccharide that is only
partially microfibrillated into the emulsion-making process at a
point where subsequent processing would provide sufficient energy
to complete the microfibrillation. It may also be possible to
accomplish some or all of the derivatization as part of the
emulsion production process; for example, the emulsion formulation
may include a charged species that will adsorb onto the
polysaccharide microfibrils, or such a species may be added during
processing of the emulsion formulation, separately or in
combination with the polysaccharide. Therefore, the derivatized
microfibrillar polysaccharides of the present invention may serve
as stabilizing additives to emulsions, with several process routes
being available to accomplish this end result.
While the choice of method may cause some variation in the
properties of the resulting emulsion, the basic benefit of improved
emulsion stability should be achieved by any procedure which has,
as its final result, the presence of the derivatized microfibrillar
polysaccharide of the present invention in the final emulsion.
Commercially, it may be desirable to supply customers with
derivatized, non-microfibrillated polysaccharide as a powder which,
when added to a formulation and subjected to high shear or other
appropriate forms of energy, will microfibrillate and yield the
derivatized microfibrillar polysaccharide of the present
invention.
This improved emulsion stability may enable use of emulsion
formulations which would not perform satisfactorily in the absence
of the derivatized microfibrillar polysaccharide. Other benefits
may include improved retention in paper, improved drainage of water
from paper systems due to association of pulp and filler fines with
the retained microfibrils, and resistance to emulsion breakage in
the presence of high salt concentrations.
The subject electrostatically derivatized materials of this
invention have also been discovered to provide rheology to aqueous
systems over a wide pH range (namely from about 2.5 to 10 or
higher) and ionic strength. This insensitivity to pH and ionic
strength facilitates use in areas where low pH and high salt
conditions exist, such as in personal care creams and lotions, food
products, and the like.
In addition to the above, the derivatized microfibrillar
polysaccharides of the present invention represent a vehicle for
providing charge, whether anionic, cationic, or both, to a given
environment. This may, as a representative example, have utility in
water treatment, where charged particles are used to flocculate
particulates and other contaminates.
The following examples indicate various possible methods for making
and using the derivatized microfibrillar cellulose of present
invention. These examples are merely illustrative, and are not to
be construed as limiting the present invention to particular
compounds, processes, conditions, or applications. Throughout this
description, "gelling" is defined to occur when G'>G", where G'
is the dynamic storage modulus and G" is the dynamic loss modulus.
This is the functional definition used in EP '011; for general
background, see Ferry, J. D., Viscoelastic Properties of Polymers,
John E. Wiley & Sons, NY, 1980.
EXAMPLE 1
Comparative
Microfibrillated, Non-Derivatized Cellulose
The following three components were weighed into a one gallon jar
at the following wt % levels:
Weight Dry Wt. Weight % Basis Bleached sulfate wood pulp 74.82 g
2.11 2.00 (5.2% moisture) (Wayerhauser Company) Germaben .RTM. II
biocide 17.50 g 0.49 0.49 (Sutton Laboratories, New Jersey)
Deionized (DI) water 3445.58 g 97.39 97.50
The cellulose quickly settled to the bottom of the jar when there
was no agitation of the slurry. The jar was shaken to disperse the
solids. The slurry was then processed in a dual stage Gaulin Model
15MR homogenizer. The secondary stage was set at about 1000 psi and
the primary stage was adjusted so that the total pressure was about
8000 psi. The slurry was processed for a total of 3.5 hours. The
resulting slurry had a much thicker consistency and the cellulose
remained suspended. When this suspension was diluted to 1.0% solids
in DI water, the resulting suspension was a viscous slurry which
did not exhibit gel properties. Over time the 1% suspension
settled, leaving free water on the surface.
EXAMPLE 2
Preparation and Microfibrillation of Carboxymethylcellulose I (CMC
I)
Isopropanol (IPA) and DI water were charged to a nitrogen sparged,
jacketed resin kettle equipped with an air driven stirrer,
stainless steel agitator, two pressure equalizing addition funnels,
a reflux condenser, nitrogen inlet, vacuum line and thermocouple.
Sulfate wood pulp (approximately 400 .mu.m length) was added to the
reactor and the mixture slurry was agitated for 10 minutes, after
which the mixture was nitrogen sparged for 1 hour while cooling the
slurry temperature to 15.degree. C. The reactor was inerted.
Aqueous 50% NaOH was slowly added to the reactor while maintaining
the mixture slurry's temperature at about 15.degree. C. The slurry
was agitated for 1 hour after completion of caustic addition.
Aqueous monochloroacetic acid (80% MCA) was slowly added to the
reactor by funnel while maintaining reaction slurry temperature at
about 15.degree. C. After MCA addition, the reaction slurry was
heated to 70.degree. C. and held for 1.5 hours. The reaction slurry
was cooled below 30.degree. C. and glacial acetic acid was added to
the reactor. The reaction mixture was then aspirator vacuum
filtered with a sintered glass funnel and a rubber dam. The wetcake
was slurried in 565 g of 80% methanol for 15 minutes using an air
driven stirrer and a grounded stainless steel beaker and then
aspirator vacuum filtered with a sintered glass funnel and a rubber
dam. This was repeated two more times. The wetcake obtained from
the previous three washes was slurried in 1000 g of pure methanol
using an air driven stirrer and a grounded stainless steel beaker
for 15 minutes to dehydrate and then aspirator vacuum filtered with
a sintered glass funnel and rubber dam. The final wetcake was dried
in a Lab-Line fluidized bed dryer (model number 23852) for 35
minutes (air-dry for 5 minutes, heat-dry at 50.degree. C. for 10
minutes, and heat-dry at 70.degree. C. for an additional 20
minutes) The carboxymethylcellulose (CMC) product was ground using
a Retsch Grinding Mill (model 2M1) with a 1 mm screen. (Although
the examples herein show washing of the product, the need for, or
amount of, washing will depend on the intended application.)
TABLE 1 CMC I Recipes (all weights in grams) Wt. Wt. Cellulose Wt.
80% Glacial Sample Cellulose (dry wt. Wt. Wt. Wt. 50% MCA Acetic #
Length Basis) IPA H.sub.2 O NaOH (aq) (aq) Acid DS 1 .about.400
.mu.m 61.36 729 73.6 60 11.8 32.2 0.16 2 .about.400 .mu.m 61.36 729
73.6 60 11.8 32.2 0.18
Preparation of CMC slurry: An 800 g 1% CMC slurry was made from
each Sample in Table 1 using the following materials:
Weight Weight % CMC 8.00 grams 1.0 .+-. 0.06% Germaben .RTM. II
biocide 4.00 grams 0.5% Deionized water 788.00 grams 98.5 .+-.
0.06% Total 800.00 grams
The container was closed and shaken to wet and disperse the CMC
solids. The solids will settle if left standing, so the container
was shaken just prior to pouring the slurry into the
homogenizer.
Homogenization of CMC slurries: The suspension was processed in the
homogenizer equipped with an agitated feed pot as follows: the
homogenizer was turned on before the slurry was loaded. An 800 gram
slurry was processed for about 20 minutes at about 3000 psi by
recycling the discharged stream from the homogenizer to the feed
pot. Pressure was monitored and appropriate adjustments made to the
primary stage handwheel to keep the total pressure at about 3000
psi. After the processing was completed, the discharge tube was
redirected so that the sample was collected and stored in a capped
jar.
Rheological testing of microfibrillated CMC I: Each
microfibrillated CMC sample prepared in Example 2 was then tested
for rheological properties. Data was collected on a Bohlin CS
Rheometer (Bohlin Instruments, Cranbury, N.J.). Dynamic mechanical
properties were measured including the dynamic storage modulus, the
dynamic loss modulus, complex viscosity, and yield stress.
Rheometer Test Conditions
Temperature Sweep: Measuring System: PP 40; 25.degree.
C.-65.degree. C.; Shear Stress: automatic; Frequency: 1 Hz;
Temperature Ramp Rate: 5.degree. C./60 seconds; Measurement
Interval: 20 seconds; Gap: 1 mm.
Yield Stress Test: Measuring System: CP 4/40; Stress:
6.0E-02-1.0E+02; Sweep Time: 60.0 seconds; Number of Steps: 30;
Temperature: Manual (25.degree. C.); No of measurements: 1;
Measurement Interval: 5 seconds.
Stress Sweep Test: Measuring System: PP 40; Temperature: Manual
(25.degree. C.); Number of Measurements: 1; Gap: 1 mm; Measurement
Interval: 5 seconds; Frequency: 1 Hz.
TABLE 2 Rheology of Microfibrillated CMC I Cellulose DS of Yield
Stress G' @ 5.75 Pa Sample # Length CMC I (Pa) (Pa) 1 .about.400
.mu.m 0.16 8.08 256 2 .about.400 .mu.m 0.18 Not Tested 192
A copy of the dynamic mechanical spectra (obtained by the stress
sweep test) of Sample 1 is given in FIG. 1.
EXAMPLE 3
Preparation and Microfibrillation of Carboxymethylcellulose II (CMC
II)
Isopropanol (IPA) and DI water were charged to a nitrogen sparged,
jacketed resin kettle equipped with an air driven stirrer,
stainless steel agitator, two pressure equalizing addition funnels,
a reflux condenser, nitrogen inlet, vacuum line and thermocouple.
Sulfate wood pulp (approximately 400 .mu.m length) was added to the
reactor, the mixture slurry was agitated for 10 minutes, after
which the mixture was nitrogen sparged for 1 hour while cooling the
slurry temperature to 15.degree. C. The reactor was inerted.
Aqueous 50% NaOH was slowly added to the reactor maintaining the
mixture slurry's temperature at about 15.degree. C. The slurry was
agitated for 1 hour after completion of caustic addition. Aqueous
monochloroacetic acid (80% MCA) was slowly added to the reactor by
funnel while maintaining reaction slurry temperature at about
15.degree. C. After MCA addition, the reaction slurry was heated to
about 70.degree. C. and held for 1.5 hours. The reaction slurry was
cooled down to below 30.degree. C. and then aspirator vacuum
filtered with a sintered glass funnel and a rubber dam. The wetcake
was slurried in 565 g of 80% methanol for 15 minutes using an air
driven stirrer and a grounded stainless steel beaker and then
aspirator vacuum filtered with a sintered glass funnel and a rubber
dam. This was repeated two more times. The wetcake obtained from
the previous three washes was slurried in 1000 g of pure methanol
using an air driven stirrer and a grounded stainless steel beaker
for 15 minutes to dehydrate and then aspirator vacuum filtered with
a sintered glass funnel and rubber dam. The final wetcake was dried
in a Lab-Line fluidized bed dryer (model number 23852) for 35
minutes (air-dry for 5 minutes, heat-dry at 50.degree. C. for 10
minutes, and heat-dry at 70.degree. C. for an additional 20
minutes). The carboxymethylcellulose (CMC) product was ground using
a Retsch Grinding Mill (model 2M 1) with a 1 mm screen.
TABLE 3 CMC II Recipes (all weights in grams) Wt Wt. Wt. Cellulose
50% 80% Sample Cellulose (dry wt. Wt. Wt. NaOH MCA # Length Basis)
IPA H.sub.2 O (aq) (aq) DS 1 .about.400 .mu.m 77.11 937.5 141.64
12.50 8.63 0.04 2 .about.400 .mu.m 61.69 750 113.32 10.00 6.90 0.06
3 .about.400 .mu.m 77.11 937.5 141.64 25.00 17.25 0.13 4 .about.400
.mu.m 61.91 750 113.09 20.00 13.95 0.15 5 .about.400 .mu.m 61.30
750 113.71 20.00 13.86 0.16 6 .about.400 .mu.m 61.91 750 113.09
20.00 13.79 0.17 7 .about.400 .mu.m 61.43 750 113.58 23.60 16.27
0.19 8 .about.400 .mu.m 61.62 750 109.38 28.00 19.32 0.23 9
.about.400 .mu.m 61.88 750 108.12 30.00 20.70 0.28 10 .about.400
.mu.m 61.43 750 106.08 35.00 24.15 0.31 11 .about.400 .mu.m 61.43
750 108.58 30.00 20.70 0.34 12 .about.200 .mu.m 62.60 750 116.41
12.00 8.28 0.10 13 .about.200 .mu.m 62.60 750 112.91 19.00 13.11
0.17
Slurry preparation and homogenizer processing were performed as in
example 2. Rheological testing was performed as described in
example 2.
TABLE 4 Rheology of Microfibrillated CMC II G' @ G' @ Cellulose DS
of Yield Stress 5.75 Pa 25.degree. C./50.degree. C. Sample # Length
CMC I (Pa) (Pa) (Pa) 1 .about.400 .mu.m 0.04 Not Tested 125 145/168
2 .about.400 .mu.m 0.06 Not Tested 139 161/160 3 .about.400 .mu.m
0.13 18.0 467 508/493 4 .about.400 .mu.m 0.15 Not Tested 467
441/429 5 .about.400 .mu.m 0.16 18.1 474 436/450 6 .about.400 .mu.m
0.17 34.7 436 452/462 7 .about.400 .mu.m 0.19 28.1 306 331/352 8
.about.400 .mu.m 0.23 21.4 148 137/145 9 .about.400 .mu.m 0.28 18.0
114 Not Tested 10 .about.400 .mu.m 0.31 14.7 12.9 12.3/12.6 11
.about.400 .mu.m 0.34 11.4 19 23.4/24.9 12 .about.200 .mu.m 0.10
8.08 339 Not Tested 13 .about.200 .mu.m 0.17 16.1 354 Not
Tested
A copy of the dynamic mechanical spectra (obtained by the stress
sweep test) of Sample 3 is given in FIG. 2.
EXAMPLE 4
Preparation and Microfibrillation of Carboxymethylcellulose III
(CMC III).
Isopropanol and DI water were charged to a nitrogen sparged,
jacketed resin kettle equipped with an air driven stirrer,
stainless steel agitator, two pressure equalizing addition funnels,
a reflux condenser, nitrogen inlet, vacuum line and thermocouple.
Sulfate wood pulp (approximately 400 .mu.m length) was added to the
reactor, the mixture slurry was agitated for minutes, after which
the mixture was nitrogen sparged for 1 hour while cooling the
slurry temperature to about 15.degree. C. The reactor was inerted.
Aqueous NaOH (50% NaOH) was slowly added to the reactor maintaining
the mixture slurry's temperature at about 15.degree. C. The slurry
was agitated for 1 hour after completion of caustic addition.
Aqueous sodium monochloroacetate was prepared by mixing 80% MCA,
50% aqueous NaOH and DI water. This solution was slowly added to
the reactor by addition funnel while maintaining reaction slurry
temperature at about 15.degree. C. After MCA addition, the reaction
slurry was heated to about 70.degree. C. and held for 1.5 hours.
The reaction slurry was cooled down to below 30.degree. C. and then
aspirator vacuum filtered with a sintered glass funnel and a rubber
dam. The wetcake was slurried in 565 g of 80% methanol for 15
minutes using an air driven stirrer and a grounded stainless steel
beaker and then aspirator vacuum filtered with a sintered glass
funnel and a rubber dam. This was repeated two more times. The
wetcake obtained from the previous three washes was slurried in
1000 g of pure methanol using an air driven stirrer and a grounded
stainless steel beaker for 15 minutes to dehydrate and then
aspirator vacuum filtered with a sintered glass funnel and rubber
dam. The final wetcake was broken into small particles using a
rubber spatula and then dried in the fluidized bed dryer for 35
minutes. (Air-dry for 5 minutes, heat-dry at 50.degree. C. for 10
minutes and heat-dry at 70.degree. C. for an additional 20 minutes)
The product was ground using the Retsch mill with a 1 mm
screen.
TABLE 5 CMC III Recipes (all weights in grams) Wt Wt. Cellulose 50%
NaMCA Solution Sample Cellulose (dry wt. Wt. Wt. NaOH 80% 50% #
Length basis) IPA H.sub.2 O (aq) MCA NaOH H.sub.2 O DS 1 .about.400
.mu.m 61.88 750 117.12 6.39 8.28 5.61 3.0 0.06 2 .about.400 .mu.m
61.88 750 114.32 9.38 12.14 8.22 5.0 0.12 3 .about.400 .mu.m 61.62
750 113.38 12.58 16.27 11.02 10.0 0.16 4 .about.400 .mu.m 61.62 750
108.38 15.98 20.70 14.02 10.0 0.24 5 .about.400 .mu.m 61.62 750
105.88 18.64 24.15 16.36 10.0 0.29 6 .about.400 .mu.m 61.88 750
102.47 21.31 27.60 18.69 10.0 0.31 7 .about.200 .mu.m 62.60 750
116.41 6.39 8.28 5.61 10.0 0.08 8 .about.200 .mu.m 62.60 750 112.91
10.12 13.11 8.88 10.0 0.16 9 .about.200 .mu.m 62.60 750 110.61
12.57 16.28 11.03 10.0 0.21 10 .about.200 .mu.m 62.60 750 117.12
15.67 20.30 13.75 10.0 0.26
Slurry preparation and homogenizer processing were performed as in
example 2 except for Sample #7, which was processed for 30 minutes.
Rheological testing was performed as described in example 2.
TABLE 6 Rheology of Microfibrillated CMC III DS of Yield Sample
Cellulose CMC Stress G' @ 5.75 Pa G' @ 25.degree. C./50.degree. C.
# Length III (Pa) (Pa) (Pa) 1 .about.400 .mu.m 0.06 14.7 281
316/310 2 .about.400 .mu.m 0.12 51.4 568 520/586 3 .about.400 .mu.m
0.16 28.1 564 607/649 4 .about.400 .mu.m 0.24 18.1 457 414/474 5
.about.400 .mu.m 0.29 21.4 298 292/303 6 .about.400 .mu.m 0.31 44.7
288 Not Tested 7 .about.200 .mu.m 0.08 4.70 238 Not Tested 8
.about.200 .mu.m 0.16 29.5 483 Not Tested 9 .about.200 .mu.m 0.21
18.1 339 Not Tested 10 .about.200 .mu.m 0.26 21.4 288 Not Tested
.sup.1 30 minute homogenizer processing time.
A copy of the dynamic mechanical spectra (obtained by the stress
sweep test) of Sample 3 is given in FIG. 3.
EXAMPLE 5
CMC Preparation with Water Washing of Wetcake
Isopropanol and DI water were charged to a nitrogen sparged,
jacketed resin kettle equipped with an air driven stirrer,
stainless steel agitator, two pressure equalizing addition funnels,
a reflux condenser, nitrogen inlet, vacuum line and thermocouple.
Sulfate wood pulp (approximately 400 .mu.m length) was added to the
reactor, the mixture slurry was agitated for 10 minutes, after
which the mixture was nitrogen sparged for 1 hour while cooling the
slurry temperature to 15.degree. C. The reactor was inerted.
Aqueous NaOH (50% NaOH) was slowly added to the reactor maintaining
the mixture slurry's temperature at about 15.degree. C. The slurry
was agitated for 1 hour after completion of caustic addition.
Aqueous sodium monochloroacetate was prepared by mixing 80% MCA,
50% aqueous NaOH and DI water. This solution was slowly added to
the reactor by addition funnel while maintaining reaction slurry
temperature at about 15.degree. C. After MCA addition, the reaction
slurry was heated to about 70.degree. C. and held for 1.5 hours.
The reaction slurry was cooled down to below 30.degree. C. and then
aspirator vacuum filtered with a sintered glass funnel and a rubber
dam. The wetcake was slurried in 650 g of DI water for 15 minutes
using an air driven stirrer and a grounded stainless steel beaker
and then aspirator vacuum filtered with a sintered glass funnel and
a rubber dam. This was repeated one additional time. The wetcake
obtained from the previous two washes was slurried in 1000 g DI
water using an air driven stirrer and a grounded stainless steel
beaker for 15 minutes and then aspirator vacuum filtered with a
sintered glass funnel and rubber dam. The final wetcake was dried
in the fluidized bed dryer for 35 minutes (air-dry for 5 minutes,
heat-dry at 50.degree. C. for 10 minutes and heat-dry at 70.degree.
C. for an additional 20 minutes). The product was ground using the
Retsch mill with a 1 mm screen.
TABLE 7 Water Washed CMC Recipes (all weights in grams) Wt. 50%
NaMCA Solution Sample Wt Cellulose Wt. Wt. NaOH 80% 50% # (dry wt.
Basis) IPA H.sub.2 O (aq) MCA NaOH H.sub.2 O DS 1 61.88 750 110.5
10.12 13.11 8.88 10.0 0.10 2 60.06 750 110.5 10.12 13.11 8.88 10.0
0.13
Slurry preparation, homogenizer processing, and rheological testing
were performed as described in example 2.
TABLE 8 Rheology of Water Washed CMC Samples Yield Stress G' @ 5.75
Pa Sample DS of CMC (Pa) (Pa) 1 0.10 37.4 724 2 0.13 34.7 855
A copy of the dynamic mechanical spectra (obtained by the stress
sweep test) of Sample 2 is given in FIG. 4.
EXAMPLE 6
High Solids Reactions
Sulfate wood pulp (about 200 .mu.m length) was charged to an Abbey
Ribbon Blender (model 0 RM, Paul O. Abbe, Inc., Little Falls, N.J.)
equipped with a spray nozzle. The reactor was sealed and the system
was inerted with nitrogen under slow agitation. Agitation was
increased to approximately 125 rpm and a solution of 50% aqueous
NaOH and DI water was sprayed into the reactor. The mixture was
mixed for one hour at ambient temperature. An aqueous solution of
sodium monochloroacetate (NaMCA) was sprayed into the reactor and
the reactor temperature was increased to 75.degree. C. and held for
2 hours. Glacial acetic acid was sprayed into the reactor and the
reactor was cooled to approximately 30.degree. C. The product was
slurried in 3 liters of water for 15 minutes and filtered using a
rubber dam. This slurry/filtration process was repeated three
additional times. The final filter cake was dried in the fluidized
bed dryer and ground in the Retsch mill using a 1 mm screen.
TABLE 9 High Solids Recipes (all weights in grams) Wt. Cellulose
Sam- (dry wt. Wt. Wt. 50% Wt. NaMCA Acetic ple Basis) H.sub.2 O
NaOH (aq) (NaMCA/H.sub.2 O) Acid DS 1 500 93 62.8 105/128.3 0 0.10
2 180 64.8 43.2 45.3/55.4 8.6 0.17
Slurry preparation: As in Example 2, except that Sample #2
(DS=0.17) was worked up as a 10% solids slurry in water. This
slurry was then mixed with more water and Germaben.RTM. II to make
the new slurry which was processed in the homogenizer.
Weight Weight % 10% CMC slurry 80.07 grams 10 00% Germaben .RTM. II
biocide 4.01 grams 0.50% Deionized water 716.88 grams 89.50% Total
800.96 grams
Since the final slurry is 10% by weight of a 10% CMC slurry, the
actual CMC level is the normal 1% by weight. Homogenization was
performed as in Example 2 except that Sample #1 was processed for
25 minutes, and Theological testing was performed as in example
2.
TABLE 10 Rheology of High Solids Samples DS of Yield Stress G' @
5.75 Pa Sample CMC (Pa) (Pa) 1 0.10 18.1 248 2 0.17 31.4 427
A copy of the dynamic mechanical spectra (obtained by the stress
sweep test) of Sample 2 is given in FIG. 5.
EXAMPLE 7
Preparation of Ready-to-Gel Microfibrillated CMC
Gels were made as described in the slurry preparation and
homogenization processing steps in Example 2 using CMC II as made
in example 3 (DS about 0.16). The gels were then processed as
follows (the following description pertains to Sample #1 in Table
11, and a similar procedure was used for all of the other
samples):
Approximately 2800 ml of isopropyl alcohol was added to a grounded
12 quart stainless steel (SS) beaker. The IPA was stirred at the
top speed of an overhead stirrer driven by house air. A SS cowls
blade on a SS shaft was used to stir the IPA. about 1400 grams of
1% CMC II gel was slowly added to the stirring IPA. The material
ratio was 2 ml IPA/1 gram gel. It took about 5 minutes to add the
gel to the IPA. The beaker was covered with plastic film and the
slurry was stirred for ten minutes.
When ten minutes had passed, the slurry was filtered through a
synthetic straining cloth. The slurry was filtered using gravity.
The slurry was covered with plastic film during the filtration to
reduce IPA evaporation. Occasionally the gel on the cloth was
stirred with a plastic spatula to help speed filtration. When it
appeared that the filtration had gone about as far as it could, the
wet cake was transferred back to the 12 quart SS beaker.
Approximately 2800 ml of fresh IPA was added to the beaker and the
slurry was again stirred for ten more minutes with the cowls
blade/air stirrer. The slurry was then filtered on a 20 cm Buchner
funnel with #415 VWR filter paper. The wet cake was transferred to
a glass crystallization dish. The dish and wet cake were placed
into an 80.degree. C. oven under vacuum overnight for drying. The
sample was dried to constant weight. The solids were ground in a
Waring Blender.
The dehydrated gels were examined by rehydration as follows: a
premix of DI water and Germaben.RTM. II was prepared.
Weight Weight % Deionized water 788.00 grams 99.49% Germaben .RTM.
II biocide 4.00 grams 0.51%
The water/Germaben.RTM. II solution was then weighed into a small
Waring blender cup along with the Ready-to-gel dry CMC according to
the recipes in Table 11. The blender cup was covered and the sample
was mixed until it appeared to be homogeneous. The resulting gel
was transferred to a glass jar. It was then shaken on a vortex
mixer. Rheological testing was performed as described in example
2.
TABLE 11 Rheology of RTG CMC Wt. % water/ Wt % RTG Yield Stress G'
@ 5.75 Pa Sample Germaben .RTM. II CMC (Pa) (Pa) 1 99.75 0.25 2.4
5.61 2 99.5 0.50 10.7 68.6 3 99.0 1.00 25.7 328 4 98.5 1.50 51.0
731 5 98.0 2.00 95.3 1400
A copy of the dynamic mechanical spectra (obtained by the stress
sweep test) of Sample 1 through 5 are given in FIGS. 6 through 10,
respectively.
EXAMPLE 8A
Acid Process for Preparation of Ready-to-Gel Microfibrillar CMC
A gel as prepared in example 3 was acidified using HCl to adjust
the pH to about 2.7. The gel was centrifuged to remove about 60% of
the water. The concentrated gel was then converted to RTG form by
mixing with IPA equivalent to 2 times the weight of the gel,
followed by filtration on a Buchner funnel and a second mix with
another 2 times weight of IPA. The wet cake was dried in a vacuum
oven.
The dried solids were rehydrated at 1% in water/Germaben.RTM. II
biocide. A small amount of baking soda was added and the sample was
mixed on the blender. Viscosity rose gradually with stirring and
the sample became gel-like. The pH was about 6.9.
Rheological testing was performed as described in example 2. G' @
5.75 Pa: 226 Pa, Yield Stress: 17.4 Pa. A copy of the dynamic
mechanical spectra (obtained by the stress sweep test) is given in
FIG. 11.
EXAMPLE 8B
Acid Process for Preparation of Ready-to-Gel Microfibrillar CMC
A second batch of gel as made in example 3 had its pH adjusted to
about 2.7 with concentrated HCl. The sample was centrifuged and
about 62% of the water was removed. About 97 g of concentrated gel
was slurried with 150 ml IPA. The pH was adjusted to 7.0 during the
stirring of the slurry by addition of a small amount of baking
soda. The slurry was filtered on a Buchner funnel, and half of the
wet cake (Sample A) was weighed into a crystallization dish for
drying. For Sample B, the other half of the wet cake was reslurried
in about 75 ml IPA. This wet cake was filtered on a Buchner funnel
and was pressed with rubber dam to remove as much IPA as possible.
Both wet cakes were dried to constant weight under vacuum, and the
solids were ground up in a Waring blender.
Sample A was mixed with water for a total solids level of 1%, and
gelled quickly. The pH was about 5.8. Sample B gelled quickly when
stirred in water at a solids level of 1%.
Rheological testing was performed as described in example 2. Sample
A: G' @ 5.75 Pa: 471 Pa, Yield Stress: 34.0 Pa. A copy of the
dynamic mechanical spectra (obtained by the stress sweep test) is
given in FIG. 12. Sample B: G' @ 5.75 Pa: 403 Pa, Yield Stress:
35.7 Pa. A copy of the dynamic mechanical spectra (obtained by the
stress sweep test) is given in FIG. 13.
EXAMPLE 9
Derivatization of Microfibrillar Cellulose
Isopropanol (602.8 g) and DI water (86.4 g) were charged to a
nitrogen sparged, jacketed resin kettle equipped with an air driven
stirrer, stainless steel agitator, two pressure equalizing addition
funnels, a reflux condenser, nitrogen inlet, vacuum line and
thermocouple. Microfibrillated cellulose of Example 1 was vacuum
filtered with a sintered glass funnel and a rubber dam. The wetcake
was slurried in 565 g of 80% isopropanol (IPA) for 15 minutes using
an air driven stirrer and a grounded stainless steel beaker and
then aspirator vacuum filtered with a sintered glass funnel and a
rubber dam. This was repeated two more times.
The wetcake obtained from the previous three washes was slurried in
1000 g of pure IPA using an air driven stirrer and a grounded
stainless steel beaker for 15 minutes to dehydrate and then
aspirator vacuum filtered with a sintered glass funnel and rubber
dam. The resulting wet cake, comprised of 36 g microfibrillated
cellulose, 228 g IPA, and 36 g DI water was added to the reactor,
the mixture slurry was agitated for 10 minutes, after which the
mixture was nitrogen sparged for 1 hour while cooling the slurry
temperature to 15.degree. C. The reactor was inerted. Aqueous 50%
NaOH (10.52 g) was slowly added to the reactor maintaining the
mixture slurry's temperature at about 15.degree. C. The slurry was
agitated for 1 hour after completion of caustic addition. Aqueous
monochloroacetic acid (7.26 g of 80% aq MCA) was slowly added to
the reactor by funnel while maintaining reaction slurry temperature
at about 15.degree. C. After MCA addition, the reaction slurry was
heated to about 70.degree. C. and held for 1.5 hours. The reaction
slurry was cooled down to below 30.degree. C. and then aspirator
vacuum filtered with a sintered glass funnel and a rubber dam. The
wetcake was slurried in 565 g of 80% methanol for 15 minutes using
an air driven stirrer and a grounded stainless steel beaker and
then aspirator vacuum filtered with a sintered glass funnel and a
rubber dam. This was repeated two more times. The wetcake obtained
from the previous three washes was slurried in 1000 g of pure
methanol using an air driven stirrer and a grounded stainless steel
beaker for 15 minutes to dehydrate and then aspirator vacuum
filtered with a sintered glass funnel and rubber dam. The final
wetcake was dried in the fluidized bed dryer for 35 minutes
(air-dry for 5 minutes, heat-dry at 50.degree. C. for 10 minutes
and heat-dry at 70.degree. C. for an additional 20 minutes). The
product was ground using the Retsch mill with a 1 mm screen. DS of
the resulting material was 0.14.
A 1% aqueous suspension of the product was mixed in a Waring
blender for 15 minutes. This produced a viscous suspension which
did not settle with time. Slurry preparation: Same as in example 2.
Homogenization was performed as in example 2, except where
otherwise stated, and rheological testing was performed as in
example 2. Yield Stress: 5.75 Pa, G' @ 5.75 Pa: 363 Pa. A copy of
the dynamic mechanical spectra (obtained by the stress sweep test)
is given in FIG. 14.
EXAMPLE 10
Alternative Cellulose
CMC was produced as in example 3 using the cellulose source and
recipe in Table 12.
TABLE 12 Alternative Cellulose Recipe (all weights in grams) Wt
Cellulose Cellulose (dry wt. Wt. Wt. Wt. 50% Wt. 80% Sample Source
basis) IPA H.sub.2 O NaOH (aq) MCA (aq) DS 1 Avicel .RTM. 62.01 750
113.49 19.00 13.11 0.16 pH-101NF (-90) 2 Solka .RTM. 61.23 750
114.27 19.00 13.11 0.19 Floc (1) 3 CTMP (2) 54.5 750 121 19.00
13.11 0.22 (1) Solka Floc (grade 300 FCC) obtained from Fiber Sales
& Development Corp., Urbana, Ohio. (2) Bleached CTMP (Chemical
Thermomechanical Pulp) Fluff obtained from SCA Graphic Sundsvall
AB, Timra, Sweden
Slurry preparation of the Solka Floc sample (Sample 2) was prepared
as in Example 2. Homogenizer processing was performed as in Example
2, and rheological testing was performed as in Example 2.
TABLE 13 Rheology Cellulose DS of Yield Stress.sup.1 G' @ 5.75 Pa
Sample Source CMC (Pa) (Pa) 2 Solka Floc 0.19 22.4 141 .sup.1 From
yield stress test/from stress sweep test.
A copy of the dynamic mechanical spectra of sample 2 is given in
FIG. 15.
EXAMPLE 11
Microfibrillation of CMC with Impingement Mixer
The samples used were 0.5%, 1.0% and 1.5% suspensions of low DS CMC
prepared as in Example 3. Each slurry weighed a total of 100 grams.
No Germaben.RTM. II biocide was used in the samples processed in
the impingement mixer. The slurries were prepared by weighing the
components into four ounce glass jars. The jars were capped and
shaken to wet and disperse the CMC solids.
Sample #1 (0.5%) Sample #2 (1.0%) Sample #3 (1.5%) CMC 0.50 grams
1.0 grams 1.5 grams DI water 99.5 grams 99.0 grams 98.5 grams
A Microfluidics Corporation Model M110 Series impingement mixer was
flushed with DI water prior to use. The pressure was adjusted to
the desired setting as the water was pumped. The impingement mixer
was run such that the DI water was pumped until it was just at the
bottom of the charge funnel. A heating bath used to control the
temperature of the impingement mixer piping was set at 50.degree.
C.
The sample jar was shaken again just before charging the sample
funnel. The sample was charged into the funnel. An electric
overhead stirrer was in the sample funnel. This was turned on to
help keep the CMC homogeneously suspended. After the first pass,
the stirrer is not needed. The sample was pumped through the
microfluidizer and out into a collection jar. The material
initially collected which contains the initial DI residue was
discarded. Processing was then continued until the entire sample
had been processed for 1 pass through the equipment.
The 0.5% solids gel was processed at 6000 psi for 4 passes. The
1.0% solids gel was processed under the same conditions. The 1.5%
solids gel was processed at 6000 psi for just 3 passes.
TABLE 14 Rheology of Impingement Mixer Microfibrillated CMC Yield
G' @ Sam- DS of Stress 5.75 Pa G' @ 25.degree. C./50.degree. C. ple
Cellulose Length CMC (Pa) (Pa) (Pa) 1 .about.400 .mu.m 0.17 4.82
79.3 97/109 (0.5% solids gel) 2 .about.400 .mu.m 0.17 Not 270
222/242 (1.0% solids gel) Tested 3 .about.400 .mu.m 0.17 Not 522
363/434 (1.5% solids gel) Tested
A copy of the dynamic mechanical spectra (obtained by the stress
sweep test) of Samples 1 through 3 are given in FIGS. 16 through
18.
EXAMPLE 12
Microfibrillated Hydrophobically Modified Carboxymethyl Cellulose
(HMCMC)
Tert-butyl alcohol (TBA, 750 g) and Hercules CMC 7H (DS of about
0.7, 100 g) were charged to a nitrogen sparged, jacketed resin
kettle equipped with an air driven stirrer, stainless steel
agitator, two pressure equalizing addition funnels, a reflux
condenser, nitrogen inlet, vacuum line and thermocouple. The
mixture was nitrogen sparged for 1 hour at 25 E C.
Aqueous NaOH (54 g of 7.5% NaOH) was slowly added to the reactor
maintaining the mixture slurry's temperature at about 25.degree. C.
The slurry cooled to about 15E C and was agitated for 1 hour at
about 15E C. A 50% solution of cetyl glycidal ether (40 g of
solution) was slowly added to the reactor by addition funnel while
maintaining reaction slurry temperature at about 15.degree. C. The
reaction slurry was heated to about 80.degree. C. and held for 3.25
hours. The reaction slurry was cooled down to about 50.degree. C.
and 9 g of 70% nitric acid was added. The mixture was cooled to
about 30E C and then aspirator vacuum filtered with a sintered
glass funnel and a rubber dam. The wetcake was slurried in 1000 g
of 85% acetone for 15 minutes using an air driven stirrer and a
grounded stainless steel beaker and then aspirator vacuum filtered
with a sintered glass funnel and a rubber dam. This was repeated
two additional times. The wetcake obtained from the previous three
washes was slurried in 1000 g of 100% acetone using an air driven
stirrer and a grounded stainless steel beaker for 15 minutes and
then aspirator vacuum filtered with a sintered glass funnel and
rubber dam. The final wetcake was dried in the fluidized bed dryer
for 35 minutes. (Air-dry for 5 minutes, heat-dry at 50.degree. C.
for 10 minutes and heat-dry at 70.degree. C. for an additional 20
minutes) The product was ground using the Retsch mill with a 1 mm
screen. The cetyl content of the resulting product was # 0.03 wt.
%. Slurry preparation, homogenizer processing, and Theological
testing were performed as described in example 2. G' @ 5.75 Pa: 319
Pa, Yield Stress: 14 Pa. A copy of the dynamic mechanical spectra
(obtained by the stress sweep test) is given in FIG. 19. While the
use of hydrophobically modified derivatized microfibrillar
cellulose has been demonstrated herein by a particular example, for
purposes of the present invention a derivatized microfibrillar
cellulose may be hydrophobically modified by carbon groups having
from about 4 to about 30 carbons.
EXAMPLE 13
Microfibrillated Hydroxyethylcellulose (HEC)
Sulfate wood pulp, tert-butyl alcohol (TBA), acetone, isopropanol
(IPA) and DI water were charged to a nitrogen sparged, agitated
Chemco reactor (3 pint reactor, Chemco, Tulsa, Okla.). The reactor
was inerted with nitrogen and the reaction slurry temperature was
adjusted to 20E C. Aqueous NaOH (50% NaOH) was added to the reactor
and the mixture was agitated for 45 minutes at 20 E C. Ethylene
oxide (EO) was charged to the reactor over a period of about 5
minutes, maintaining the reaction slurry at 20E C. After EO
addition, the reaction slurry was heated to 50E C and maintained at
50E C with agitation for about 45 minutes. The reaction slurry was
then heated to about 90E C and maintained at 90E C with agitation
for 30 minutes. The reaction slurry was cooled to about 50E C and
70% nitric acid was added. The reaction slurry was cooled to below
30E C and then aspirator vacuum filtered with a sintered glass
funnel and a rubber dam. The wetcake was slurried in 600 g of 80%
acetone for 15 minutes using an air driven stirrer and a grounded
stainless steel beaker and then aspirator vacuum filtered with a
sintered glass funnel and a rubber dam. This was repeated two
additional times. The wetcake obtained from the previous three
washes was slurried in 600 g of 100% acetone water using an air
driven stirrer and a grounded stainless steel beaker for 15 minutes
and then aspirator vacuum filtered with a sintered glass funnel and
rubber dam. The final wetcake was dried in the fluidized bed dryer
for 35 minutes (air-dry for 5 minutes, heat-dry at 50.degree. C.
for 10 minutes and heat-dry at 70.degree. C. for an additional 20
minutes). The product was ground using the Retsch mill with a 1 mm
screen.
TABLE 15 HEC Recipes (all weights in grams) 70% Sample 50% Nitric #
Cellulose TBA IPA Acetone H.sub.2 O NaOH EO Acid MS 1 46.0 517.8
8.6 7.9 63.5 13.0 16.1 14.6 0.7 2 49.77 517.8 8.6 7.9 59.73 12.7
10.6 14.6 0.8 3 49.77 517.8 8.6 7.9 59.73 13.0 19.5 14.6 1.3
Slurry preparation and homogenizer processing were performed as in
example 2, except that fewer passes were required to process to a
gel.
TABLE 16 Rheology of Microfibrillated HEC Sample MS of HEC Yield
Stress (Pa) G' @ 5.75 Pa (Pa) 1 0.7 1.66 43.6 2 0.8 3.65 10.3 3 1.3
2.98 2.96
A copy of the dynamic mechanical spectra (obtained by the stress
sweep test) of Samples 1 though 3 are given in FIGS. 20 through
22.
Drainage Aids in Paper Manufacture: the following examples
demonstrate the effectiveness of derivatized microfibrillar
polysaccharide as a drainage-improvement aid.
Drainage measurements were performed on a Canadian Standard
Freeness (CSF) tester, using a bleached kraft pulp consisting of
70% hardwood and 30% softwood. All freeness testing was performed
in hard water having a pH of 7.95-8.05, alkalinity of 50 ppm (as
calcium carbonate), and hardness of 100 ppm (as calcium carbonate)
using TAPPI method T 227 om-92. A pulp consistency of 0.3% was
used. Higher CSF values indicate better (faster) drainage.
The following results were obtained using RTG microfibrillated CMC
prepared in example 7, which has a degree of substitution of about
0.17 charge group per anhydroglucose unit. All loadings are
calculated as percent of additive (dry basis) relative to pulp.
EXAMPLE 14
RTG CMC Sample Material Alone
% RTG CMC Material (based on pulp) CSF 0 210 0.025 274 0.050 285
0.100 315 0.200 317
EXAMPLE 15
RTG CMC Sample Material and Hercules Reten.RTM. 1232 (R-1232)
CSF VALUES % RTG Material 0.1% 0.2% (based on pulp) R-1232 R-1232 0
380 462 0.1 485 591 0.2 526 608 0.4 587 637 0.6 572 671
EXAMPLE 16
RTG CMC Sample Material and Hercules Kymene.RTM. 557H resin
(K-557H)
A constant 2:1 ratio of K-557H to material was employed. (Kymene is
a registered trademark of Hercules Incorporated.) Two different
starting pulps were used, one with a relatively high freeness, and
one relatively low.
% RTG Material % Pulp 1 Pulp 2 (based on pulp) K-557H CSF CSF 0 0
184 413 0.1 0.2 281 531 0.2 0.4 321 565 0.4 0.8 382 574
EXAMPLE 17
RTG CMC Material and Hercules Kymene 450 resin (K-450)
A constant 2:1 ratio of K-450 to sample material was employed. Two
different starting pulps were used, one with a relatively high
freeness, and one relatively low.
% RTG Material % Pulp 1 Pulp 2 (based on pulp) K-450 CSF CSF 0 0
184 413 0.1 0.2 285 536 0.2 0.4 335 546 0.4 0.8 357 562
As with ordinary CMC, the sample material extends the wet and dry
strength activity of additives such as Hercules Kymene 557H or
Kymene 450 resin. Thus an advantage of the use of the sample
material is the provision of a combined wet strength/dry
strength/drainage/retention aid.
Use in paper sizing compositions: the following examples relate to
use CMC II as made in example 3 having a DS of about 0.15 in
connection with compositions used in paper sizing.
EXAMPLE 18
A 600 ml beaker was used to combine 66.0 grams of Precis.RTM. 787
ketene dimer (available from Hercules Incorporated, Wilmington,
Del.; Precis is a registered trademark of Hercules Incorporated),
1.5 g of CMC II (as made in example 3, DS about 0.15), and 232.5
grams of DI water. The pre-mix was dispersed by stirring for two
minutes using a Tekmar Ultra-turax SD45 rotor-stator high shear
mixer (Tekmar Company, Cincinnati, Ohio) at a power setting of 50.
This pre-mix was then quickly poured into the feed chamber of the
impingement mixer. With mechanical stirring at about 250 RPM,
premix was passed through the impingement mixer with its pressure
set at 5000 psi. The emulsion was collected and a second pass was
made. The second pass product was collected in a clean jar, a stir
bar was added, the jar was capped, and then cooled in a 5 to
15.degree. C. water bath.
EXAMPLE 19
Same as Example 18, using 66.0 g Precis ketene dimer, 1.5 g of the
sample material, 66.0 g of 50% aluminum sulfate (18H.sub.2 O)
solution in water, and 166.5 g DI water.
EXAMPLE 20
Same as Example 18, using 66.0 g Precis ketene dimer; 1.5 g of the
sample material; 132.0 g of a solution containing 25% (wt) aluminum
sulfate (18H.sub.2 O), deionized water, and sufficient alkalinity
to raise the pH to 4.0; and 100.5 g DI water.
EXAMPLE 21
Same as Example 18, using 66.0 g Precis ketene dimer; 75.0 g of a
2% solution of CMC 7M (DS of 0.7) (Hercules Incorporated,
Wilmington Del.) in deionized water; and 132.0 g of a solution
containing 25% (wt) aluminum sulfate (18H.sub.2 O), deionized
water, and sufficient alkalinity to raise the pH to 4.0; and 27.0 g
DI water.
EXAMPLE 22
3.0 g of CMC II (as made in example 3, DS about 0.15) were
dispersed in 465 g DI water for 5 minutes using the high shear
mixer at a power setting of 50, then given three passes through the
impingement mixer at 5000 psi. As in Example 18, 66.0 g Precis
ketene dimer were combined with 234.0 g of the sample material in
DI water gel, stirred using the high shear mixer at a power setting
of 50, then given two passes through the impingement mixer at 5000
psi and cooled.
EXAMPLE 23
4.0 g of CMC II (as made in example 3, DS about 0.15) was dispersed
in 400 g DI water for 5 minutes using the high shear mixer at a
power setting of 50, then given three passes through the
Microfluidizer at 5000 psi to give a gel.
In an 8 ounce wide mouth jar, 176.0 grams of Precis 787 ketene
dimer and 224.0 grams of DI water were combined. The pre-mix was
sheared in the high shear mixer for 5 minutes at a power setting of
50, then quickly poured into the feed chamber of the impingement
mixer. With mechanical stirring at about 250 RPM, the premix was
passed twice through the impingement mixer set at 5000 psi
150.0 g of the gel made above was combined with 150.0 g Precis
ketene dimer 44% emulsion, and stirred 5 minutes using the high
shear mixer at a power setting of 50.
EXAMPLE 24
In an 8 ounce wide mouth jar, 66.0 grams of Precis 787 ketene
dimer, 1.5 g of pre-sheared, solvent exchange dried material as
made in Example 7 (DS of about 0.16), and 232.5 grams of DI water
were combined. The pre-mix was sheared in the high shear mixer for
5 minutes at a power setting of 50, then quickly poured into the
feed chamber of the impingement mixer. With mechanical stirring at
about 250 RPM, the premix was passed through the impingement mixer
at 5000 psi. The emulsion was collected and a second pass was made.
The second pass product was collected in a clean jar, a stir bar
was added, and the jar was capped and cooled in a 5 to 15.degree.
C. water bath.
The following pages provide testing results for the sample
emulsions using TAPPI Standard Method T560:
TABLE 17 Surface Sizing of Example 18 through Example 24 Size
Emulsions (formulation weight in grams) (Pre-shear) (MF gel) (MF
gel) (RTG) Example # 18 19.sup.1 20 21 22 23.sup.1 24 Precis 787
66.00 66.00 66.00 66.00 66.00 66.00 66.00 Microfibrillated CMC 1.50
1.50 1.50 1.50 1.50 1.50 50% Alum 66.00 25% Alum pH 4.0 132.00
132.00 2% CMC 7M 75.00 DI Water 232.50 166.50 100.50 27.00 232.50
232.50 232.50 Total 300.0 300.0 300.0 300.0 300.0 300.0 300.0
Rotor-stator Shearing 2 min.@50 2 min.@50 2 min.@50 2 min.@50 2
min.@50 2 min.@50 5 min.@50 Impingement Mixer Shearing 2X@ 2X@ 2X@
2X@ 2X@ 2X@ 5 kpsi 5 kpsi 5 kpsi 5 kpsi 5 kpsi 5 kpsi Rotor-stator
Gel Shearing 5 min.@50 5 min.@50 Impingement Mixer Gel Shearing 3X@
3X@ 5 kpsi 5 kpsi .sup.1 Examples 19 and 23 gave emulsions which
broke overnight and were not suitable for surface sizing the next
day. The failure of Example 19 is most likely due to low pH
resulting from the presence of the 50% alum, and can be corrected
by raising the pH of the alum. Without being bound by any
particular theory, it is known that aluminum can appear in a
polymeric form, and so may form a co-acervate, at higher pH. In
general, # the pH of the alum, poly-aluminum chloride, or other
aluminum salts should preferably be as near as possible to the pKa
of the derivatized microfibrillar cellulose. Thus, in Example 18
the addition of low pH 50% alum solution gave an emulsion with poor
stability, while similar recipes in Examples 18 and 20, made
without alum or with alum whose pH had been raised to pH 4.0, #
gave good emulsions. In Example 23, adding the microfibrillated gel
without a second impingement mixer shearing as in Example 22 gave
an emulsion which was not stable overnight, and thus could not be
size tested the next day.
The emulsions from Examples 18, 20, 21, 23, and 24 were then tested
in sizing compositions, and the results are shown in Chart 1. The
procedure used to obtain this data was as follows: all samples were
made with 5% (wt.) D-150 starch (Grain Processing Corp., Muscatine,
Iowa). Five pieces of paper and a wet pick-up sheet for each run
were size pressed using a wet nip size press. Each sheet was dry
pressed with a drum dryer at 220.degree. F..+-.5.degree. F. for 20
seconds. The weight of wet the pick-up sheet was determined before
and after the size press to give wet pick-up percent. Hercules Size
Testing (HST) was performed on each paper sheet (5 per run)
utilizing TAPPI procedure T560.
CHART 1 ##STR1##
EXAMPLES 25-27
A series of emulsions was made using Aquapel.RTM. 364 sizing agent
rather than Precis ketene dimer as the size, with the formulations
shown in Table 18. In each case the sample was sonicated on a
Branson 350 Ultrasonicator at a power setting of 6. Samples of fine
paper were made on a continuous Fourdrinier-type machine, using the
emulsions and sizing tested after 100 hours natural aging using a
standard HST ink resistance test (TAPPI Method T-530) using a 1%
formic acid ink. Chart 2 shows the HST sizing results, which show
the samples to be at least as good as or better than three
commercial controls using Hercon.RTM. paper sizing agent.
TABLE 18 Example 25 Example 26 Example 27 Aquapel 364 (1) 10 10 10
Carrageenan 2% (2) 50 CMCII 1 (prepared in Example 3, DS about 0.15
Ambergum .RTM. CMC 2% (3) 50 pH 4 Alum 20 20 20 Reten .RTM. 203 20%
(4) 5 5 5 Diocide AMA 415 0.02 0.02 0.02 Water 14.98 63.98 14.98
(1) Aquapel 364 Ketene Dimer sizing agent - Hercules Incorporated
(2) Carrageenan - GenuGel .RTM. Carrageenan Type LC-5, Hercules
Incorporated (3) Ambergum - Type 99-3021, Hercules Incorporated (4)
Reten 203 - Cationic resin, Hercules Incorporated (Ambergum,
Aquapel, Hercon, Genugel, and Reten are registered trademarks of
Hercules Incorporated)
CHART 2 ##STR2##
Papermaking
The paper used in the sizing examples was made at pH 7 from a 75:25
blend of hardwood and softwood pulps beaten to a Canadian standard
freeness of 525 and formed into sheets having a basis weight of
65.1 g/m.sup.2. Hercon 70, Hercon 79, and Hercon 115 sizing agents
were all added at 0.06%, based on the pulp (corresponding to 1.2
pounds per ton). Laboratory water was used, having a hardness of 50
ppm, an alkalinity of 25 ppm, and a pH of 8.1-8.4.
Use in food and personal care compositions: the following examples
relate to the use or derivatized microfibrillar polysaccharides in
food and personal care products.
EXAMPLE 28
Use as Fat Replacer, Viscosifier in Food Applications
Fat Free Mayonnaise Model System Ingredients (wt. %) 1 2 3 RTG
Microfibrillated CMC 0.8 Microfibrillated CMC 0.8 water 76.2 76.2
77.0 starch (Pureflo)* 4.0 4.0 4.0 maltodextrin 10.0 10.0 10.0 salt
2.0 2.0 2.0 vinegar (12% acetic acid) 4.0 4.0 4.0 egg yolk 3.0 3.0
3.0 viscosity (cps) 42000 45000 6000 *marketed by National Starch
and Chemical Co.
Procedure 1: RTG Microfibrillated CMC prepared in example 7 above
(DS about 0.16) was dispersed in water with agitation. Starch and
maltodextrin were added with agitation.
The mixture was heated to 80.degree.-90.degree. C. followed by
cooling to 15.degree.-20.degree. C. Egg yolk then vinegar were
added. The product was then mixed by means of a colloid mill. This
mixing consists of one pass through a Greerco colloid mill model
W250V-B (Greerco Corp., Hudson, N.H.) with an emulsion rotor and
stator at a 0.001 inch gap setting. The texture of this product is
then evaluated after 24 hours.
Procedure 2: to a 1% microfibrillated CMC gel as made in example 3
above (DS about 0.16) the balance of the water was added Starch and
maltodextrin were then added with agitation. The mixture was heated
to 80.degree.-90.degree. C. followed by cooling to
15.degree.-20.degree. C. Egg yolk then vinegar were added. The
product was then mixed by means of a colloid mill. The texture of
this product is then evaluated after 24 hours.
Procedure 3: starch and maltodextrin were added to water with
agitation. The mixture was heated to 80.degree.-90.degree. C.
followed by cooling to 15.degree.-20.degree. C. Egg yolk then
vinegar were added. The product is then mixed by means of a colloid
mill. The texture of this product is then evaluated after 24
hours.
Evaluation: viscosity was measured with a Brookfield (Model
DV-II+), 20.degree. C., helipath, 5 rpm spindle C, program S93.
The appearance of the product containing either RTG
Microfibrillated CMC or Microfibrillated CMC is that of a gel that
holds its shape for a period of time when cut and does not
synerese. When a portion of the product is lifted with a spoon or
spatula, it does not appear to have stringiness of excessive
tackiness; the texture is described as short. These are subjective
textural features similar to that of reduced fat spoonable
dressings and mayonnaises.
EXAMPLE 29
Use in Personal Care Products
Moisturizing Lotion Phase Ingredient Wt % A DI water 81.85
Hydrophobe Modified 0.24 Hydroxyethyl Cellulose (Natrosol .RTM.
Plus 330, Hercules Incorporated) Glycerin 2.00 Disodium ethylene
diamine 0.05 tetraacetic acid B Petrolatum 5.00 Mineral Oil 3.00
Glycol Stearate 2.00 Isostearyl Benzoate 2.00 Parraffin 2.00
Dimethicone 0.50 RTG microfibrillar CMC as in 0.36 example 7 (DS
about 0.16) C Germaben .RTM. II (preservative) 1.00
Procedure: the Part A ingredients were combined, mixed until the
water-soluble polymer dissolved, and heated to 60-65.degree. C. All
Part B ingredients were combined except the microfibrillar CMC, and
heated to 60-65.degree. C. until homogeneous. The RTG
microfibrillar CMC was then dispersed into part B, and part B was
added to part A with vigorous agitation, which was continued until
the mixture was smooth and homogeneous. It was then cooled to
30.degree. C., and part C was added.
Properties pH 5.7 Viscosity* (cP) at 25.degree. C. 16,600
Appearance Milky-white emulsion Stability >5 weeks at 50.degree.
C. *Complex viscosity in linear viscoelastic regime was measured
with a Bohlin controlled stress rheometer.
This example demonstrates the ability of the RTG CMC material to
stabilize an oil in water emulsion, performing a role typically
performed by surfactant/cosurfactant network forming systems.
Night Cream Phase Ingredient Wt % A DI water 78.3 Glycerin 2.00
Germaben .RTM. II (preservative) 0.50 Hydrophobically Modified 0.72
Hydroxyethyl Cellulose (Natrosol .RTM. Plus 330, Hercules
Incorporated) B Avocado Oil 4.00 Isostearyl Isostearate 4.00 Octyl
Stearate 3.00 Isopropyl Myristate 3.00 Propylene Glycol Isostearate
4.00 RTG Microfibrillar CMC as in 0.48 example 7 (DS about
0.16)
Procedure: the ingredients for part A were combined and mixed until
the water-soluble polymer dissolved. The ingredients for part B
were then combined, and part B was added to part A with vigorous
agitation, which was continued until the mixture was smooth and
homogeneous.
Properties pH 6.0 Viscosity* (cP) at 25.degree. C. 30,200
Appearance Creamy white emulsion Stability >5 weeks at
50.degree. C. *Complex viscosity in linear viscoelastic regime was
measured with a Bohlin rheometer.
This example demonstrates the ability of the RTG CMC material to
stabilize an oil in water emulsion, performing a role typically
performed by surfactant/cosurfactant network-forming systems. The
RTG CMC also is processed at room temperature, while typical
surfactant/cosurfactant systems require heat.
Alpha-Hydroxy Acid Anti-Age Cream Phase Ingredient Wt % A DI water
71.9 Glycerin 5.4 B Cetyl Alcohol 3.2 Glyceryl Stearate and PEG-100
4.8 Stearate (Arlacel 165, ICI) Stearic Acid 1.6 Isopropyl
Palmitate 4.8 Mineral Oil and Lanolin 4.8 Alcohol (Amerchol L-101,
Amerchol) Dimethicone 1.6 RTG Microfibrillar CMC as 0.6 made in
example 7 (DS about 0.16) C Lactic Acid (88%) 0.3 Germaben .RTM. II
(preservative) 1.0
(As used herein, "anti-age" refers to that category of epidermal
lotions and creams intended to contribute to a more youthful
appearance by the user, such as by the reduction or removal of
wrinkles.) Procedure: The ingredients for part A were combined and
heated to 75.degree. C. The part B ingredients, except RTG
microfibrillar CMC, were then combined and heated to 75.degree. C.
until homogeneous. The RTG microfibrillar CMC was then dispersed
into part B. Part B was next added to part A until the mixture
became smooth and homogeneous. The mixture was then cooled to
40.degree. C., and part C was added. This composition was
formulated at pH 3.5-4.0, and stabilized with microfibrillar CMC
rather than with typical xanthan, clay mixtures.
Properties pH 3.7 Viscosity* (cP) at 25.degree. C. 932,000
Appearance Glossy white, stiff cream Stability >5 weeks at
50.degree. C. *Complex viscosity in linear viscoelastic regime was
measured with a Bohlin rheometer.
This example demonstrates the ability of the RTG CMC material to
stabilize an oil in water emulsion at low pH.
High SPF Organic Sunscreen Cream Phase Ingredient Wt % A DI water
63.9 B Cetearyl Alcohol and Cetearyl 6.6 Phosphate (Crodafos CES,
Croda) C Benzophenone-3 5.0 Octyl methoxycinnamate 7.5 Octyl
Salicylate 5.0 Menthyl Anthranilate 5.0 Octyl Stearate 5.0 D RTG
Microfibrillar CMC as in 0.3 example 7 (DS about 0.16) E NaOH, 18%
0.6 F Butylated hydroxytoluene 0.1 Germaben .RTM. II (preservative)
1.0
Procedure: The ingredients for part A and part B were combined and
heated to 70.degree. C. Part C was then added separately, mixing
after addition of each part C ingredient. Part D was then added
with vigorous agitation, which was continued until the mixture
became smooth and homogeneous. Part E was then added, the mixture
was cooled to 45.degree. C., and part F was added.
Properties pH 5.9 Viscosity* (cP) at 25.degree. C. 613,000
Appearance Light, off-white cream Stability >5 weeks at
50.degree. C. *Complex viscosity in linear viscoelastic regime was
measured with a Bohlin rheometer.
This example demonstrates use of microfibrillated CMC with organic
sunscreen.
Formulation of a TiO.sub.2 Based Sunscreen Lotion Phase Ingredient
Wt % A DI water 67.2 Disodium ethylene diamine 0.1 tetraacetic acid
Propylene Glycol 5.0 B C.sub.12-15 Alkyl Benzoate 3.0 Butyl
Stearate 3.0 Myristyl Myristate 4.0 Sorbitan Oleate 0.1 RTG
Microfibrillar CMC as in 0.6 example 7 (DS about 0.16) C Germaben
.RTM. II (preservative) 1.0 Titanium Dioxide 6.0 D Octyl Palmitate
9.0 Polyglyceryl-10 decaoleate 1.0
Procedure: the ingredients for part A were combined and heated to
50.degree. C. All of the part B ingredients, except microfibrillar
CMC, were combined and heated to 60-65.degree. C. until
homogeneous. The microfibrillar CMC was then dispersed into part B,
which was then added to part A with vigorous agitation, and
agitation was continued until the mixture was smooth and
homogeneous. The ingredients for part D were combined and mixed
well. Part C was added to the AB emulsion; then, with moderate
agitation, part D was slowly added to the emulsion and cooled to
30.degree. C.
Properties pH 7.1 Viscosity* (cP) at 25.degree. C. 33,900
Appearance Glossy, white emulsion gel Stability >5 weeks at
50.degree. C. *Complex viscosity in linear viscoelastic regime was
measured with a Bohlin rheometer.
This example demonstrates use of microfibrillated CMC with
inorganic sunscreen. The present invention has of necessity been
discussed herein by reference to certain specific methods and
materials. The enumeration of these methods and materials was
merely illustrative, and in no way constitutes any limitation on
the scope of the present invention. It is to be expected that those
skilled in the art may discern and practice variations of or
alternatives to the specific teachings provided herein, without
departing from the scope of the present invention.
The present invention has of necessity been discussed herein by
reference to certain specific methods and materials. The
enumeration of these methods and materials was merely illustrative,
and in no way constitutes any limitation on the scope of the
present invention. It is to be expected that those skilled in the
art may discern and practice variations of or alternatives to the
specific teachings provided herein, without departing from the
scope of the present invention.
* * * * *